I don't get it. If DDI has 100,000+ suscriptions, maybe many more, then it must be the most profitable portion of the D&D section of WotC, right? Then why is it so crappy? OK, it isn't simply and only "so crappy" but it is much less than it could be and, more so, hasn't really evolved in quite some time, except for the worst with online-reliance. Why has Adventure Tools been stalled out on Monster Builder for, what, over a year? Why isn't there a Dungeon Builder, an Adventure Builder, a World Builder, tools for house ruling and class making?
The obvious further question is that even with DDI so crappy and they still have 1-200,000 subscriptions, how well would it do if it was actually really good? I have an unfortunate speculative answer, and that is probably not much better. It might get some disenchanted former subscribers back, but how many would that account for? A 10% increase?
I am reminded of much of my high school experience where I quickly learned that if I put in about 50% effort I could get an A-, 70% effort an A, and 90% an A+...being of a somewhat unmotivated (lazy) temperament, I decided that I would rather put in 50% and get the easy A- than work a bit harder for the A or A+. I'm wondering if WotC is doing the same: they're going for the best ratio of time expenditure, effort and money spent vs. profit. If offering a truly excellent DDI was proportionally more lucrative than offering a crappy DDI, they'd do it. But my guess is that it just doesn't make enough difference.
This is not to say that they aren't working on improving DDI in some form or fashion (such as the potentially Frankensteinian Virtual Tabletop), but they haven't in a year or more so it is easier to be skeptical than hopeful. The above-mentioned Builders wouldn't be that hard, or time-consuming, to create. My point being, if they haven't already then they probably won't, not until they figure out something that they think has a huge profit potential, like VTT.