Plane Sailing said:- why are gaining powers from a different class so expensive? You've already spent a feat to multiclass, why additional feats to swap one of your perfectly good powers for one of those perfectly good powers?
I wouldn't say the feat your spending to multiclass is much of a cost. If you look at the things it gives you, it seems to be signifcantly more then you'd otherwise expect to get out of a single heroic feat. If it gave you even more on top of that it would be pretty insane.
On the fighter/magic missle discussion.....yeah I doubt the fighter is going to take magic missile. But in addition to scorching blast there's also ray of frost....a little slowing utility might not be bad at all for the fighter. And the lower attack bonus from less int can be made up for by the fact that it targets fortitude rather then ac.