What was the alternative? We weren't going to go to war against both the Taliban AND the opium growing warlords who are slightly less crazy and slightly less Islamist. If there are any Western style liberals in Afghanistan, they are too few to build a society around.
Frankly, we are probably doing the best we can do with the poor hand we are dealt and the force we are willing to apply.
The only hope for long term success is to open these Muslim countries up to the Gospel and let it do the work we are unable to do - which is change these cultures and their enslaved mindsets from within.