The interesting part, having some experience in the field, is that it can be much more lucrative to release a smaller 'disposable' game than an elaborate one that keeps players coming back for more. Just look at angry birds. In the case of delteria (or other knock off graal servers) it isn't hard to skin the game and make it appeal to another client base who may or may not have had interest in previous servers... if it costs 99 cents, the average consumer doesn't think much about it, but if you get 10,000 clients spending 99 cents, it's pretty clear that this is worth a little effort.
Take it on the other side where you have 100 or 200,000 players who have high expectations and have already paid their 99 cents... you can see where this goes.