They've thinned down their creative departments so much that I'm left wondering just who is doing any work on anything at the company.
WotC has a history of using freelancers for creative work, iirc.
So when they introduce a whole new class, I'm a bit deflated because it means work has gone into that, that could've been put into the billion and one other things I'd rather see happen, like fixing the assassin, or updating all the monster statblocks to MM3 format, or fixing any number of balance issues, or working on the functionality of the Monster Builder.
Some of what you mention there isn't game design work, though. The monster builder work calls for a software developer, not a game designer. Updating statblocks sounds more like intern-level work.
So, my question to you is, "Would you rather see new content, or would you rather they fixed all the current content?"
Looking at the print market - I expect few people are going to pay for reworked old content. Folks expect errata for free, and gripe from here to the heavens if they try to repackage old content in a new book. There's no direct payoff for fixing things if the market isn't going to pay for them.
DDI is another matter - for a subscription, the customers may well find "bug fixes" to be valuable enough to be pleased and continue subscriptions for them. But for any particular piece of old content, only some segment of the population will care if you fix it. So, you need to do a massive job of it for it to be effective. Would doing so pay off? We certainly don't have the information to say.
In the history of RPGs, perfection of old content has never been the norm. Players are generally used to dealing with a certain level of cruft - this is why house rules are so common. I think that's actually healthy - it keeps us out here in the field thinking. Beyond a certain point, filing off the rough edges ceases to pay off for either the consumer or the producer.
We (gamers, not just you and I, personally) are likely to disagree on what that certain point is, though.