arcane has always had the simplest rotation of all classes in wow. this is true. and the burst you get from it is extraordinarily easy to see first hand in heroic dungeons and trash mobs. any fool warlock can roll a mage and perform deceptively well when you're in heroic zul'aman.
who cares.
this is harder to see on boss fights where the target lives longer than your mana pool.
the skill involved in playing an arcane mage comes from playing the "manage your cooldowns" mini game. you will need to conserve mana, arcane power, and mana gem for the bloodlust/heroism that will inevitably pop during the fight. is there enough time to do that before and have it be available? when would be the optimal time to evocate? if aoe is involved, arcane will not be nearly as effective as fire (new TB boss, anyone?). will you have to move when you pop your arcane power? i sure hope not!
the fact of the matter is, if you take 2 similarly geared mages you will be able to discern who managed their cooldowns wisely and who was newer to the raiding scene. that gap in dps is the proof that mages were designed to be easy to play and hard to master. just like every other class in wow. what some don't grasp is that you simply can't play a mage like you play every other class. if you approach mage the same way you approach warlock then you will complain that its too easy, but your dps will plummet on a long fight. you can't play a mage like you play your paladin. you will complain that its too easy but then you will never interrupt or spellsteal, you will ignore the number of stacks of arcane blast you had for the first quarter of health the boss has, and your dps will plummet on a long fight. etc. etc. for other classes.
arcane is not about rotation, its about mana and cooldown management and timing.
i could argue that playing a hunter is even easier than mage. you right click on a mob and autoshot it while your pet goes apes*** on it. there, now you are dpsing. even a mage has to actually press a button at least!
but if a hunter wants to actually be competitive with dps then he/she will have to do a LOT more than that. again, easy to play and hard to master. same concept, just different approach. that's only one broad example but i think i'm approaching wall-of-text status here so i'll stop.