Go drink some more coffee.
Wizards may have chosen the setting, but Turbine did some things very well. From my perspective you couldn't be more wrong about the combat - that is THE way to take a turn based table-top game and make it a real time FPS.
Did you play it? How far did you get?
DDO is instanced; the only un-instanced areas are public areas and PVP pits. The most a griefer can do is try to trick into letting them in your party or annoy in public places. Either way they can't kill you, and they can't get your stuff.
That said I suspect F2P will make my ignore list much bigger.
As to why you would play DDO.. for one thing it has the best combat of any MMO. Fast, real-time, twitch driven. It has no competitors there except for late unlamented Hellgate. And many of the rules still resemble D&D v3.5.
It's the only MMO I have stuck with, and I have tried many. WoW? No way.