Is WotC charging too much for their books?
No, if anything they're not charging enough. Books are expensive to produce, and becoming more expensive every year.
The one thing I
really don't like when it happens is if they reduce the page count at the same time as increasing the price. I mean, logically I understand it... but I don't like paying more for less.
Sort of.
I'm starting to think that WotC would be well served turning D&D into a fairly deluxe (and quite expensive) boxed starter set/core rulebook combo, supported by a small number of equally-expensive expansion boxes... and doing almost all of the rest of the support online via the DDI.
I do think that the Core Rules for the game are
way too big, and should be cut down to a single volume of about the same size as the 4e "Rules Compendium".
However, I don't think the individual books are too big. The last book I bought was the aforementioned "Rules Compendium", and I thought the format was
fantastic.
Are the production values too high?
No. If they want D&D to go mass-market, they need to keep the production values high. There's an argument for not going that route... but it's not an option while Hasbro hold the brand.
Is color necessary on every page or in every piece of art?
No, but... It's part and parcel with the high production values that the books are full-colour. I wouldn't mind seeing books in black and white, but I understand why they're just not done.
Is hardcover good bad or indifferent?
The gamebooks I use frequently get a pounding, and hardback goes a long way to mitigate the damage. (I haven't used the RC enough to see how it holds up. It's worth noting that my 3.5e Core Rulebooks have had hundreds of hours of use across almost a decade, and are completely intact.)
My preference is very definitely for hardback, at least in Core Rules. And yes, I know that's not entirely consistent with some of the other stuff I've said in reply to other questions.
When you buy a book from WotC do you feel like your money was well spent?
I don't buy a lot from WotC, but that's mostly due to 4e. For the most part, when I
have bought a book from WotC, I have considered it money well spent. The exceptions are pretty notable (3e's "Deities & Demigods", "The Book of Exalted Deeds", and especially "Scourge of the Howling Horde").
Ultimately... this is a cheap hobby. Once you've got the Core Rulebooks for your game you don't actually need anything more. 4e breaks this assumption slightly, in that you're almost certain to
want more (at least PHB2 and more MMs), but they're not required... and anyway, if you're playing much 4e you probably want a DDI sub, which is very reasonably priced. In fact, WotC's major problem is that you
don't need anything more.