What's funny is that I see Wizards using the same philosophy with their Dungeon Tiles as they do with their miniatures... bundling products to maximize variety in the smallest amount of shelf space. Which is great for them as far as getting their product on shelves in places that do not cater strictly to D&D or gamer fans (like Barnes & Noble, Borders etc.)
What they are voluntarily giving up, however, is the "mass" market of product geared specifically towards DMs. Thus we don't see things like "box o' orcs", where it's a bundled box of 20 orcs of various types. And by the same token, we don't get "folder o' trees", where it's a mass of 8 pages of die-cut tree tiles in 1, 2, 3, 4, 6, and 8 inch squares.
They have basically allowed other companies to fill those voids that the hardcore DMs want and need filled. Miniature Singles selling stores that allow you to buy a dozen kobold Commons of the same type so you have a mass of minions at your disposal... and other print companies to mass produce poster maps, flip-maps, tiles, and counters that are more generic and more universally useful to a hardcore DM, but might not have as much of a sales punch or flair to them to an impulse shopper when seen on the spindle rack of Barnes & Noble.
But because I think many D&D players would use exclusively Wizards products if they could... they are disappointed when Wizards do not produce the products they are hoping for or want. Thus, they have to look at outside companies to find what they need, which I think quite a number of players (given their druthers) would rather not do. But it's a voluntary decision on Wizards' part to let these other companies fill the void that they themselves are not interested in filling.