Of course it is. Look at Christian countries. Wherever you go, the churches are built in the European manner, the clothes of the clergy are the European ones. Converts had to become Christian and thus assimilate to a more Western way of life, where Western = Christian.
If you go to countries where Muslims spread, you will find that the mosques are not built in the Arab architecture, but in the local architecture, peoples clothes didn't suddenly change and become Arabised. Muslim =/= Arab. Islam is all about flexibility and accommodation. Anybody who knows an ounce about Sharia law would now that it is all about flexibility and interpretations.
Thankfully I've read a few law books and have gained a general understanding of Common and Shariah law, and Shariah is anything but inflexible. If anything, its flexibility is the reason you get extremists - they get to bend it so much.