Sometimes OSes are deemed obsolete for whatever reason, and browsers -- all of them! -- simply stop developing for those OSes. This means that you're at least shelling out the cost for a new OS, which can be (1) painful (if you're using Windows or Linux in some cases) or (2) impossible (e.g. if you're using Mac OS X and Apple has decided that your hardware is "end-of-lifed" -- e.g. PowerBook G4). If you're one of the unlucky ones to be in the latter category, you actually have to shell out enough money for at least some upgraded hardware (perhaps in addition to the OS), or possibly a brand new (or newer but still used) computer, which will likely be a lot more painful than just shelling out for the OS.
The key point is that Google Apps are tied to browser versions, and browser versions are tied to OS versions, and OS versions aren't exactly consistent in their support or end-user coverage. Users who figured their current setup works well enough for now, and who for many years haven't had any reason to upgrade will now be forced to if they want to make use of those Google Apps -- or, they can take the much less costly route and simply not use Google Apps, or deal with "simple HTML mode" or whatever.
The worst part about this that irritates me most, though, is that many of these systems simply don't have anything wrong with them except that someone, somewhere, arbitrarily decided they were "too old". So perfectly functional pieces of equipment now lack functionality because enough people have arbitrarily decided that they "don't have" that functionality anymore, even where it might actually be possible.
On the plus side, it does mean that no one has to support old browsers' quirky and always-varied interpretations of the same chunk of code...
The upgrade difficulties in large organizations are often brought upon themselves with poor adherance to public standards and insufficient test automation. Last I checked, Google itself is a large organization, and they don't seem to have any worries over the rate at which software gets updated.
Google is a big organization in the business of developing web software. Most organizations are in other businesses. If I'm running a construction company, it doesn't make sense to have IT consultants come in each time a new version of something comes out. If it works, it's best to leave it alone, modulo security fixes.
Do you feel the need to upgrade your house's plumbing system and electrical each time an innovation happens? That's how most people feel about software.
When the electrical grid connecting to your house get updated and no longer supports your installed system you upgrade as well or you don't get electricity.
I don't. Why would I want to upgrade my fixtures twice a year if they're working and look fine? I'd be happy to keep the same set for 20 years, myself.
Is it really worth carrying a metaphor out to its absurd conclusion? A web browser does not exactly equate to a plumbing fixture, yet they both have maturation cycles that prompt people to upgrade over time. Browser technology moves faster than plumbing, I don't think anyone would be terribly surprised by that revelation, yet when plumbing technology advances I will upgrade. I will upgrade sooner rather than later because the savings in time and energy pay off over time, just like with browser technology. The further behind the cycle I remain, the more it costs me to modernize in the future and the more it costs me to stick with the old. The literal time period is completely irrelevant.
