NPE safety and sum times deal with issues that developers face on the day to day, long before the product ever gets used by end users in the first place.
NPE issues are also very very difficult to chase down.
"very very difficult" on what scale? How many "verys" before it gets really hard?
Again, the proof is in the pudding. You take a language that doesn't make any special efforts to protect against nulls (eg. Java), and you take Kotlin that does, and the difference in the number of problems associated with NPEs is barely noticeable.
Perhaps some automation offered by Kotlin for dealing with NPEs makes developers' experience more pleasant / easier, but the Java side just isn't hard enough to make this a substantial benefit.
And, just to not be misunderstood: I'm not saying that automation in how to deal with missing values is bad, not at all! It's good. But, strategically, there are much bigger problems / juicier targets than NPEs. If you compare this to health, then NPEs are a headache, while misunderstood requirements are a cancer. It's great if you can treat both, but if you have limited resources, then cancer gets a priority treatment.
NPE issues are also very very difficult to chase down.