Why Haven't They Made a Proper D&D Game Yet?

More of a rant than anything else, but why on earth haven't they made a turn-based D&D game yet? Online or Offline. Every one I've seen, heard of or played has been action oriented. Neverwinter Nights, Dungeons and Dragons Online, even the upcoming Neverwinter game (now possibly in jeopardy due to Cryptic Studios en route to being sold) have all been real time.

You can't say it's due to difficulty. All of the rules are already in place, and errata fixes any possible exploits (infinite free attacks) and if necessary, simply hold off on certain classes or feats or powers, what have you.

You can't say it's not due to lack of an interested audience. I know many who have been waiting for the official release of the D&D 4.0 tools so that they could DM games online. One of the biggest problems with tabletop games these days is finding players to form a steady group.

Here's what I propose. Free to play the game, and downloading it gives you the basic classes, DM tools and monsters AKA Player's Handbook 1, Dungeon Master's Guide and Monster Manual 1 along with the Essentials set. Then, simply sell other pieces as addons based on the extra books that were released. Hell, make a bundle of them so you get the actual pdf of the book with the addon. A boxed copy of the game would be available with certain perks, but it would be completely playable as a game without needing anything else.

DM's would create lobbies to DM games, much like the lobbies in FPS. In some cases, DMs won't even need to actually create an adventure. They'll have the option to, of course, but players are always given the option to simply play through a randomized, level appropriate dungeon. Monsters are always balanced against the group, and DM's (or players via a voting system) can up or lower the difficulty.

There would also be a main city hub for trade, grouping, RP and what not, equipped with shops, taverns, lovely scenery, etc. etc. There would be one main server, and the city would be broken up into shards so that if one is too busy, you can simply go to City 2, or 3, or so on and so forth much like the Guild Wars implementation. 

Books aren't the only monetary source. Pre-made campaigns can also be sold in booster packs, where the loot is predetermined from a list, much like in dungeons we know today. There would be a small selection available at launch, and the rest sold in booster packs.

I think it sounds nice. But I can't help but see the problems inherent in the system. Firstly, creating any non-combat campaign would be incredibly difficult, if not impossible to do within the system. Not much of an issue for a good DM who creates an RP specific room, or if you use the 4.0 system which is fairly strict in what things do. Loot is also an issue, which means it should be taken out of the players and DMs hands and put to randomized, except in the previously mentioned dungeons. Exp would be taken out as well.

I'm terribly confused why this route hasn't been taken, other than possible copyright concerns. It wouldn't take away from the tabletop crowd as that is a completely different environment, and those who prefer that crowd would most likely stay there. I know I would play both. What about you?