Perhaps we also shouldnt assume that Islamists will automatically screw everything up (as if it isnt completely messed up right now).
Look at the AKP and its success in stabilizing and helping the Turkish economy to grow. We have to stop with the perpetual boogeyman reflex everytime we discuss politics in the Muslim world.
The Brotherhood is not the AKP which, notwithstanding the hysteria of the right-wing, is no more theocratic in nature than the German Christian party. The aggressively secular military would boot them if they so much as detected that the prime minister was playing to the gallery of the hot-for-Shariah crowd.
But your wider point is well taken. Islamism is not Bin Ladenism. As the case of Lebanon demonstrates, towelheads can be co-opted by the establishment. All political movements begin with radical manifestos and impassioned rhetoric of ushering in the New Jerusalem and end predictably in champagne toasts to the monarchy. It's all very well promisng the earth when you're in opposition, but made accountable to the electorate, radicals shed their luster. Such has been the legacy of all oppositionists since the first advanced ape put on a tie, cultivated a frown and set out on a speaking tour.