I don't think there's anything wrong with MMOs as a genre, there's quite a few MMORPGs that are very fun and very good.
I just really don't think it's the right direction for the TES series, which are all very successful single player RPGs, I don't see a need or a purpose to suddenly shift to making an MMORPG when you are already quite adept at making RPGs that win crazy awards and make bank.
The entire idea seems kind of counter productive.
I don't think TES needed to go in this direction at all, especially after the success of Skyrim. That being said however, releasing an MMORPG will attract a different audience, which in the long run will only increase the reach of TES which will of course, bring in more cash.
I'm more excited about the idea of an even larger map. After playing Morrowind and Oblivion I'd love to be able to travel all over Tamriel and watch as the culture and scenery changes as you travel.
The idea of multiplayer isn't something I'm looking forward to, but there seems to be a way of deciding whether you play on your own, with friends etc so I'm hopeful.
I just don't want to lose the rpg style that TES seems to have perfected. In the past when I've tried out MMORPG's, I've never been able to connect and immerse myself as well as when I've played single-player rpg's. But, I can't dismiss what I haven't experienced so I'll just wait for more information and a release date and go from there. I want to believe them when they say it's the best of both worlds but I have a suspicion they've bitten off more than they can chew with this venture.