@fantasycrusader: So, your basic reason for wanting the post revisions turned off is "I don't want them" or "I'll not use them". Just because you don't want to use a tiny little bit more space (we're talking about TEXT here, it compresses very well, you know), you want to disable a potentially very handy cover-your-ass feature. This makes no sense to me.
I mean, what does turning revisions off actually do? Well, it makes it not save revisions, but there is no major UI impact whatsoever. Revisions won't appear in the revisions box. That's it. That's all that happens. It doesn't get any faster, there's no significant improvement anywhere from disabling it, it just takes potentially very handy functionality and castrates it, to no benefit whatsoever.
Furthermore, the post revisions feature is not targeted at the CMS crowd, it's targeted at the single blogger, the one who posts on his own and is trying to make good posts. Revising drafts several times is a commonplace activity, just because you knock off your posts in one take doesn't mean everybody works that way.
The majority of users don't mind the post revision feature. But for those power users who simply must have it, there's a simple disable code. Adding actual option checkboxes for something that most people do not care about doesn't make any sense from a UI standpoint.