Yes, that seems op if you put it that way
but instead, compare her to other immobile mages:
Vel'koz has 3x as much range as annie, AOE TRUE DAMAGE BURST, extremely good kiting potential, more raw damage
Viktor... don't get me started. More range, more annoying "pet" ult, much better at zoning, consistent DPS
Lux has enormous range if slightly less raw damage. However she brings pick potential and extremely long-ranged ult
Syndra has superior burst, raw damage, pick potential and almost double range
Brand has % damage, much better range, extremely potent AOE damage, tank shredding....
And to other immobile short range mages:
Vladimir is much tankier, heals back like lunatic, resourceless, AOE damage amp, untargetable... oh god why
Cassiopeia MUH DPS
Also, if enemy picks Annie you can just pick one of these "I don't want to acknowledge your presence in lane" champions such as Morgana, Galio or Sivir and just waveclear for days while Annie helplessly cries under her turret.