Honestly I can’t recall which gen dropped it, but presumably the moment they reached their EoL for the last non-64 bit device they had no reason to maintain the development cost of having a 32bit OS, maintaining support for communication between 32 and 64bit apps, nor the cost to users (doubling the size of the resident system memory, confusion of some apps running on some device but not others, etc).
And then knowing that if you drop 32bit then you can gain space on your silicon.
What irks me is that devs saw the first 64bit devices come out, and didn’t go “I should recompile my code”. Honestly the fact there are so many new apps made for pc that aren’t 64bit is mind blowing to me.
> Honestly the fact there are so many new apps made for pc that aren’t 64bit is mind blowing to me.
Assuming you mean Windows, there are still a nontrivial number of PCs in the wild that are running a 32-bit OS. It's not huge -- about 1.5% of gaming PCs according to the Steam survey, probably a bit higher for home and office computers -- but either way it's enough that building applications as 64-bit-only is problematic.