Honestly, I've yet to see my friend really have any issues with movement. At most, if he needs an enemy brought to him, using Aero's teleport to bring the enemy closer so he can use all his AP on attacks works perfectly well. Combine that with Pyro's Haste and he can kill an enemy in one round with just the auto attacks, he does so much damage with those alone.
One of the better tactics I've found is actually to teleport him directly into the middle of a group. He takes a bit of damage, but so do all the enemies. Then he throws out a spinning attack and tends to finish at least one or two normal enemies off. It's astoundingly effective. It's all about positioning and using the varied class abilities effectively. No one class is going to be good at everything. It's a lot easier to focus on way with each class and then put that to use by combining their strengths.
So your friend had to spend points in strength, const, speed, AND int to get some small level of viability. Mages only need int, and would definitely be able to do whatever your friend does more effectively.
Yes, mages ARE good at everything. They heal, they tank, they kite, they murder, at low low discount prices. Like I said in my original points, the main problem is every single magic school, and there are _5_ of them, scale with int. You can use them all. They all have fantastic summons for tanking with 1 turn CDs, mobility skills, amazing shields that grant insane damage absorption, more than just having armor or resistances, low cooldown heals, 1 turn cooldown CC, etc.
