The thing is warriors and rogues don't need frequent pauses, zooming in-out, rotating, positioning, retreating and all that. Of course while soloing and dealing with large clustered mobs like the ambushes in Denerim backalleys, mages would be much more faster. But most of the battles in the game are small scale and short ranged, often fought in tight quarters.
Yes, most of the battles are small scale and perfectly suited to be solved by way of Fireball, Flame Blast and Walking Bomb. In fact, a caster mage is only slowed down if the enemy troops are scattered over a large area, which means they have to be induced to move into an area no larger than 15 metres diameter, for the usual Fireball treatment.
The only trick is to keep your own troops out of the firing line (by setting them all to "Ranged" and letting them hang back) or simply to go solo most of the time because you don't need the extra fire power and they would only slow you down. The 'time played' thingy keeps on ticking even when the game is paused; in that sense it gives you an objective value how much time you - the player - had to invest, regardless of how few or how many combat rounds there were in game time. Going solo if you don't need help dramatically cuts down on the amount of pausing and micro management necessary.
The thing is, when the rogue is positioning for her first backstab then the mage is already done with that group and moving on to the next one. 
And where did you get the 'retreating' thing from? A CC/nuker retreats for no one, except maybe for some elite and bossy critters. Drakes, revenants and bossy ogres are an absolute pain for mages whereas rogues and warriors eat them for breakfast, but that's the exception to the rule. And there aren't a whole lot of them in the game anyway.
And I wager that even Archie goes down faster for a soloing mage than for a team led by a rogue or warrior Warden... When talk came around to Morrigan attending the funeral in shapeshifted form, over in another thread, I loaded a rooftop save for a mage to investigate and fraps the funeral. Fiona toasted Archie in no time flat without even trying hard, while the team was safely stashed in the far corner of some platform. Eamon, Kardiol and Irving kept Fiona's back free by dispatching the few darkspawn she had pulled following Archie around until he finally settled down to meet his fiery sparky end.
Lest I be misunderstood - I don't want to diss warriors or rogues. I love my Reaver/Champion tank, and I love my DW dagger rogues. But I want to light the fire of competition, in the hope that inspiration may result for people to nuke and shred enemies in new and entertaining ways.