I have a firm answer, but need to qualify it a bit. When it comes to rpg party-based games, then turn-based combat is a must! The point is when having several different party members in your group, each of which presumably has a wide variety of spells and/or abilities, I think turn-based combat is definitely the way to go, as it allows a far richer and more interesting tactical style of combat, where thinking is encouraged and if designed well, required, rather than frantic clicking like in an action rpg.
Having said all that, I don't want turn based combat for all my games and genres!
No way.
I'm a first person shooter gamer as well, and love playing the real-time combat style in those games. While I could see playing a turn-based first person shooter as an interesting experiment, it definitely should not be the norm like real time is with traditional first person shooters.
And, don't get me wrong, I also enjoy an action rpg from time to time, when in the mood. So I can appreciate real time combat in rpgs as well, I'm not an "extremist" and hate it with a passion or something. But as I said, if talking about a hard core, party-based, rules complex/heavy D&D style of rpg, then for me, turn-based is supreme!