That's because the koran is one big lecture telling followers how to live, as opposed to a collection of some rules mixed with a whole lot of stories from which lessons can be drawn from that we see in the Bible.
Plus be careful what you wish for. Over the centuries it did become more lax. Wahhabism is a recent advent, a return to fundementalism and stricter code of conduct. Not exactly a reformation, but in a sense it is, one retreating to a more restrictive past and the repression, oppression, and terrorism that follows.
There was the schism between Sunni and Shiite early on, and various sects emerging from them since such as the mystical and funkier Sufism. But a radical departure, especially as it retreats back to itself, is not happening anytime soon.
