I like your wrench example, so I'm going to appropriate it. Suppose Bob invents a wrench. But, when he presents it to you, he tells you it's really good at knocking nails into wood. And, it can certainly do that: it's sturdy, it's got heft, a handgrip, etc. But, you and most other people who spend some time with it realize that it's not really the best nail driver around, and that it's got these other great torque functions.
That is, debatably, what the idea of a D&D designed by people hostile to at least many flavors of charopp looks like. D&D, since 2E when I really got into it, has been a game with tons of fiddly bits. A dizzying array of spells and magic items with their own rules accompanying them, dozens if not hundreds of classes, kits, prestige classes, etc. It's hard to think of it as a game that isn't built around the idea of "here's a bunch of weird, sometimes clunky stuff, put it together how you see fit and see what happens."
If you weren't interested in at least some form of charopp -- by which I mean finding interesting, often counterintuitive ways of fiddling with the mechanics to realize various concepts, archetypes, etc. -- then you should find another game. You should find a game that is more straightforward, for lack of a better term. Something that is either simpler and more direct (viz. the rise of OD&D) in its mechanics, or something that is less fiddly (e.g., M&M, which has a very different approach to stuff like charopp).
If you're interested in playing 3E D&D, then you're at least in part interested with putting together stacks of various abilities in various combinations. That's the way the leveling works, it's the way spell lists works, it's the way magic items work, it's the way feats work, etc.
Hence, the Bob and his wrench analogy. Taking Wotmaniac's description of the designers as true (I have no idea one way or the other), then they clearly have misunderstood things on a fundamental level. And, it's not like charopp was anything new, people had been doing it with vigor for at least a decade before 3E hit the shelves. Why should they be treated as authoritative or even helpful if they have clearly made such mistakes? And, there are so many problems with that as an approach -- namely the fact that many people were involved in the process. Legislative intent is the act of looking for a friendly face in the crowd, as one jurist said -- it's a generally disfavored practice.
More generally, no, I don't think there's much merit in "author's intent." Barring cases that amount to typos, which are hopefully rare (I can only think of 2), I don't see why the author's voice, all things being equal, is any more authoritative than any thoughtful reader or critic. Pathfinder makes an eloquent argument against trusting the game designers. And, that's especially true when at least a significant portion of them have not demonstrated themselves to be useful resources. I'm not sure what that says for RAW v. RAI -- I don't find either one of those a useful concept as I've said before.
