Any change on 32-bit machines will require special CPU instructions, massive Lisp slowdowns, or massive integer math slowdowns.
Considering you can't even buy a new 32-bit machine anymore, however, I don't really see this as a major problem.
Re:GNU Emacs 23.2 released
by koenigdavidmj on Saturday May 08, 2010 @08:56PM
(#1331275)
>Considering you can't even buy a new 32-bit machine anymore, however
Netbooks.
I think the choice they make is to spend their very limited time on more useful features. I'm sure many of the core Emacs developers would be very happy if someone would fix this limitation. It would be a very invasive change, a fair amount of work.