I've often said here that I prefer "short" games, which is to say, games whose rulebooks take up no more than about 64 pages. In thinking about it, I realize that that's not quite true. OD&D plus its four supplements amounts to quite a bit more than 64 pages and I use rather a lot of those pages in my Dwimmermount campaign. Upon realizing this, I initially thought I wasn't being consistent on this point.
Then I spent some time considering what I meant by saying I prefer short games and it quickly became clear to me: I don't mind games whose page count runs longer than 64 pages if most of those pages are devoted to something other than game mechanics. That is, having, say, 50 pages devoted to spell descriptions, 20 pages devoted to magic items, and 100 pages devoted to monster write-ups isn't necessarily a problem for me. Granted, I generally prefer games that describe all those things in fewer pages, but I don't find the notion of 170 pages devoted to detailing more "stuff" I can use with the rules a priori wrong or problematic. However, I do think there's a problem when, for example, a game requires 30 pages to detail a combat system, including all sorts of special cases that'll likely never come up in play. That's too much for me.
I'm more of a "How many rules do you need to pretend to be an elf?" kind of guy. To my way of thinking, the answer remains "No more than 64 pages, preferably less." However, I do see value in having lots of monsters, spells, magic items, and similar sorts of things, since not every referee is able to make these things up easily (or at all). Where I start to get twitchy is when we see new character classes, races, magic systems, and the like, since they almost always add options to the game at the cost of unnecessary complexity and it's that complexity I find a big turn-off these days. I much prefer to have a simple, solid rules core that doesn't take much effort to master.
Any game system possessing lots of rules I find myself ignoring wholesale is probably too complex for my tastes. That's why I prefer OD&D over AD&D, even though I played "AD&D" throughout my early gaming years. The reality, of course, was that I simply put aside lots of AD&D's rules back then, like initiative and weapon speed factors. Having already been there, I no longer have any interest in playing a game whose rules I have to pare down to something more manageable. That strikes me as a foolish endeavor, when I can much more easily find a straightforward simple set of rules to which I can add more "stuff," as I wish.
Obviously, where one draws the line is different for each person, but, for me, the rules line encompasses a fairly small area, while the "stuff" line is much larger. I still prefer to make up a lot of the the "new stuff" that appears in my campaign, but I have no qualms about swiping stuff from other sources. I don't see anything wrong with buying books filled with spells, monsters, and magic items. Heck, I don't think there's anything wrong with buying adventure modules. The key, as with everything, is to treat all of this stuff as supplements to your imagination rather replacements for it.
I think the main thing that irks me about so many of the hobby products we've seen since the end of the Golden Age is that too often they did seem to be replacements for individual imagination rather than spurs to it. They reduce gaming to yet another form of passive consumer entertainment and that's a pity, because it (largely) wasn't like that when I entered the hobby and there's no reason why it need be nowadays either. That's why I'm so down on gigantic rulebooks and story-based adventure modules and campaign settings. I think they make roleplaying not much different than other types of entertainment rather supporting the unique qualities that make it a pastime like few others.