I'm A Banana
Potassium-Rich
However, with a system like 4E, the base system itself is actually very simple. As, in my not entirely humble opinion, it should be. When the base system is simple, it's easy to figure out what kind of effect each change will have on the game.
You're right, but I think we may have different definitions of "simple." IMO, if you're talking about 4e's skill system, okay, it's simple. If you're talking about 4e's combat system...then it is lousy with fiddly bits with great meaning and meaningless bits that seem significant. IMXP, of course.

CroBob said:I do think options should be part of basically every RPG, but at what point do you give up on writing a rule book at all and just hand people a business card that says "Do whatever you want"?
This is part of why I'm a big supporter of the OGL. The best way to ensure that someone can find a suite of options that suits their own table well is to ensure that there is an ecosystem of options that are more diverse than any one person will ever functionally need. Let everyone make modifications to your base system, and it is going to wind up adapted to EVERY niche, even the ones you've never thought of or the ones you personally don't have any interest in. The OGL enabled things like roleplaying in fantasy Africa, detailed rules for fictional sex and romance, a 300+ page compendium of historical weapons and armors, telekinetic flying jellyfish as a PC race, and more. I might not care about any of those personally, but a plentiful ecosystem makes it more likely to find what I DO care about. At least one "gritty" d20 variant has already been mentioned in the thread, and there's at least a dozen more where that came from.
WotC doesn't need to provide everything (though they might want to provide some of the most common desires). They just need to provide a platform -- an engine -- that can run anything, and to give everyone permission to do anything they want with it. The magic of the OGL is, in part, that it supports the natural way that people play the game anyway.