I agree with most of what you say, but I don't necessarily hold truck with this statement. IMHO, the rules cater to the DM's ability to customize, just as you are doing. Both the DMG and PHB make it clear that some things are exclusively his choice (prestige classes being a classic example). The assumption is made that the DM is going to customize the game to meet his needs, so they provide you with as many options as possible.
It is true that the supplements are more often catered to players than DMs. This is a simple case of economics...there are more players than DMs, and even though DMs buy more books, players outnumber the DM by a wide-margin.
D&D is written to the generic, not the specific, because WotC knows, through market research, that DM's tend to customize. It's a pointless exercise, because the DM is expected to make those choices and decisions....and rather than impose a set of rules that some DMs won't like, they chose a lack of specialization, to place that power back in the DM's hands. That way, one DM can use the rules as written, while another DM can use it to tailor his game as much as desired. Thus, you can accomadate such diverse settings as Midnight, Conan and the Forgotten Realms under the same d20 roof.
I also have to agree with WayneLigon's assessment that the idea that 'being like a video game' is bad, or that D&D is like that (not that you were specifically saying that, BU). Quite frankly, we should all be so lucky as to enjoy a game that's as enthralling as Knights of the Old Republic or Prince of Persia, IMHO. Never mind that it's an apples-to-oranges comparison...like saying that the game Guillotine is a poor game because the French Revolution keeps replaying and has no consequences. It just seems silly, to me.