Sharia law is a very emotive term, but it was originally intended to be reinterpreted.
The Koran does not have a legal framework, it's full of ideas and values. When Mohammed died a group of revered Islamic scholars used the Koran as a basis for Shariah law. When it was completed these very scholars made a big point about it being of its time, and that it should be reinterpreted every couple of generations.
The problem is, their advice was ignored, that's why Shariah seems so archaic.
In any event starting a democracy can be a messy business, they've only experienced a dictatorship. As long as democracy is entrenched people will eventually stop feeling that Islamic fundamentalism is the only alternative to Mubarak style dictatorship.