Thing is it's easy to need more than XX bits of stuff total, it's a lot rarer to want that in a single array in a high level language.

32-bit CPUs lasted for several decades in desktop computers, and I don't see it going away anytime soon. Personally, I think a lot of what average users are using computers for at the moment wouldn't need anything more than that. In most cases, 4GB is still a lot of memory... but it's easy to waste.