Ah, you're one of those "it's not intended, so it's cheating" people. It's not cheating, it's playing your class to the max, albeit unintended. I won't have to show up to raids suboptimally. They expect me to play to the best possible, not the best intended by blizzard.
Aside from that, we're more than fine. We're nowhere near the middle of the pack. Frost can do reasonably well in skilled hands, and fire needs a bit of love single target. There's many more worse classes/specs. Guild needs caused me to reroll mage from shadowpriest in MoP. Shadowpriests are always middle or below, barely get changed in any way, yet don't QQ 24/7. As said before, even if we're second to locks and come 5.2 possible one or twoother classes, our output is fine.
Regarding mana for frost/fire.. You'd still be hard pressed to go oom, as mana gem isn't arcane-exclusive. They probably wouldn't allow mana needs to cause us to run oom as frost or fire following your regular rotation.
Stop acting like you're well near bottom when mages are still king, and will be above middle come 5.2 in one of three specs surely.