I hope nothing makes it necessary, but I do hope it becomes commonplace. It's such a better experience to complete a ballot leisurely in one's own home, being able to discuss it with my own family and referencing a plethora of materials, than having to go out of my way to wait in line and have prepared everything ahead of time (and, hopefully, remembered it).
I don't equate easy with better. I miss the sense of community inspired by going to the local polling place and seeing your neighbors. It's a ritual that has value. Yeah it takes some effort, and if people want to make it a federal holiday, that's cool too.
Mail-in ballots have so many more issues with them - lack of privacy (so more room for coercion and harvesting), they make auditability more difficult.
Regardless of whether you think the relaxed voting requirements of 2020 led to widespread fraud, it inspired enough distrust that both parties should be advocating to bolster the reliability, auditability, and trustworthiness of the voting process, not decrease it further. The only thing that sucks more than losing an election is losing it under suspicious circumstances. Subject people to that enough times, and it doesn't lead anywhere good, regardless of your political team. Instead, create and enforce policies that improve trust rather than erode it.
Are you certain your vote was counted and not lost? I vote in person because I know when I mail things they don't always get where I intended them to be (and especially when there is a deadline in place)
In my country, I can just bring the letter and put it in a special mailbox in the city hall in the weeks before the vote. I would trust the mail system, too, but that's beside the point.
In my case I complete my ballot ahead of time and drop it in a ballot box, which are distributed around my city. Then I get an email from my county clerk when my ballot has been counted.
I think the concern about things getting lost in the mail is reasonable, but is a separate issue; the mail system is supposed to be a highly trustworthy distribution system for sensitive documents. Hell, it's how you get your passport. That's why it's a state department (in the US, anyway) in the first place: it's an essential government function to have a communications channel with a given citizen.
I've been concerned about cuts made to the USPS leading up to the previous election, both because of the obvious impact on the USPS's ability to handle election materials, but also because of the potential impact on the arrival of other essential, time-sensitive documents. (Not essential, but my mother's anniversary card to myself and my partner fully bounced this year, after three weeks in transit. We only live 130 miles apart.)
My point is: threat models that center on the mail system somehow being unreliable are a valid concern, but missing the point.
This problem was solved at least as far back as ancient Rome. The solution was and is the secret ballot. If nobody gets to see your ballot before it goes into the box, and if it can't be tied back to you, nobody can hold you to a vote. Thus, even if someone threatens your life, bribes you, etc, the secret ballot preserves your ability to vote your conscience.
Usually bribers will want some proof, like a photo of your vote, when you go inside and there are election observers and you're not allowed to use your phone it's more difficult to provide that proof.
a) you get bribed by some external sweepstakes or ad or any which way to vote for a candidate you genuinely don't support.
b) you in your home get hit by a vandal with a specific mission to make you vote for their candidate. Remember, this felon does not know when you get your ballot nor when you voted.
Hell, which is more likely to be tracked down? The Musk trials will take months. that felon will be arrested before the week ends.
a) bribing is more probable, happened by foreign country here this Sunday
b) it's a lot more dangerous for the entire society, it's not a vandal in your home, if anonymity is not implemented by voting process, then the local gang leader will force you (and all your neighbors) to vote for him, at the date he will tell you and you won't be able to do anything as he will be in power after these elections and will make possible to fake future elections.
I find this threat model unreasonable and it reeks of conspiracy-style thinking; there are so many points of failure in it that I have trouble believing this argument is being offered in good faith. I'll continue to engage in good faith, but I want to state that skepticism.
(a) I don't think it'd be possible to extort votes in this manner in on a significant enough scale to influence an election without it being obvious that it was happening. All it would take is a few people to go "Oh yeah, someone broke into my house and held a gun to my head" to spark an investigation. Moreover, to a degree, this level of coercion is already occurring: a party platform of cutting taxes on your income bracket is effectively a bribe. A party platform that they'll cut healthcare funding if their candidate doesn't take a particular office is a gun to your head.
See also: the publicly known instances of 'vote bribing', e.g. Ben and Jerry's offering free ice cream, or Musk or Cards Against Humanity offering money/tickets/etc to people who have voted/make a plan to vote.
(b) for a vote-extorter, how would you verify that I voted as demanded? what if I don't mail that ballot? what if I deliberately screw up my signature? what if I submit my ballot before you extorted me? what if I vote in person later, invalidating my mail-in ballot? It's possible someone with access to the inner workings of the voting judgement process could detect some of these, but at that point, again, it's already compromised.
(c) If you have the resources to possibly (1) identify vote extortion targets (2) successfully threaten them in such a way that it would influence their vote (3) validate that they did indeed vote as you've demanded, you surely have the resources to attempt a more directed attack on, say, the mail system or the vote system itself. Trying to extort individual citizens en masse would radically increase the odds of detection of your operation.
(d) how do you know your election judges aren't under gunpoint? how do you know they haven't been bribed? Or your county clerk?
Yes, in most cases coercion isn't as obvious as someone literally pointing a gun to your head (though in some cases it could be, there's nothing to prevent it). Typically it'll be something more subtle, like the "vote bribing" scenarios you outlined, but with the added pressure of the person providing the incentive literally being able to stand over your shoulder and watch you fill out the ballot, then take the envelope from you and deposit it themselves into a drop box.
As I've said before, coercion doesn't need to be overt to be effective. Just a small amount of social pressure applied over a large number of people is enough to make a significant difference. That's why typically there are laws banning campaigning right outside polling places. Now what if the "polling place" is the entire country, over a period of multiple weeks? How are you going to enforce that?
Consider also that the electorate being able to trust that elections are free and fair is nearly as important as them actually being so. Its not enough to just say "that's probably not happening at sufficient scale to make a difference"; you need to be able to convincingly demonstrate to voters it actually isn't. Having a system that's robust to these types of cheating schemes (as in-person, secret paper ballot elections have been for centuries past) is the best way I know to do that.
I hope nothing makes it necessary, but I do hope it becomes commonplace. It's such a better experience to complete a ballot leisurely in one's own home, being able to discuss it with my own family and referencing a plethora of materials, than having to go out of my way to wait in line and have prepared everything ahead of time (and, hopefully, remembered it).