"...or they would have to give every melee several more tools to stay in range so they can dmg you."

you mean like charge, hamstring, intervene, shadowstep, fleet footed, sprint, death grip, pursuit of justice...

should i go on?

I think you're kind of missing his point though, which is mages already have a game of 'cat and mouse' with those kind of range increase/range decreasing abilities, and it is reasonable balanced (the way you listed several abilities off 4 classes is kind of misleading, in truth most classes have maybe 1 or 2 gap closers just like mages have 1 or 2 range increasers). If you throw in something like Arcane Repulsion it's going to deliver the mages a massive advantage, unless you also throw the melee classes another gap closer. Whilst I've not inspected all of them I've not seen any new gap closers (before someone mentions Heroic Leap remember that is tied on the same CD as charge).

Personally I think keeping this low enough that frost mages can spec into it would be overpowered considering how hard it is already for most classes to get to a good frost mage, however move it a couple tiers down it would be a good talent to make arcane pvp viable which would be nice.

And of course, as always things are prone to change in Cataclysm so this speculation may prove totally unfounded when they remove all slows from frost spells, or give rogues a 30s sprint, etc.

If the fire talent that repels attackers gets to stay, then so does this one.

Or the repulsion could have its one minute cooldown wasted on a pet.

So, you know, balance.