Well, waste depends on your perspective. Most of the features are a little more advanced than OS3.9, and so take up more RAM. On top of that, it's all rewritten in C, which is bigger and less efficient, but means easier development. How much RAM does a 3.9 machine with USB, TCP/IP, and all the patches that would bring it to similar functionality use?
I didn't mean to imply that OS4 does or doesn't make justifiable use of 64MB; I haven't used it, so I'll refrain from comment. I just object to the philosophy of "what the hell, we've got RAM to burn" on principle. Code from that perspective, and pretty soon you're going to have a bunch of irritated users wondering where all their memory has gone.
I guess one needs to decide if the OS should use more modern features, or stick with the old-fashioned, bolt-on-what-you-want philosophy...
I don't think those are at all mutually exclusive, if there's a suitably well-defined framework for bolting on or taking off. (Unless you mean OS4 specifically, I dunno whether it has a good framework or not.)
