There are valid reasons to have prohibitions on alcohol. Look at the former 18th Amendment. Look at our draconian Cannabis laws: simple possession can get you a year in jail. Is that any more just than a caning for drinking alcohol? The substance prohibitions of the Muslim faith, along with those of most other major religions, are usually based on something that transcends the religion.
Trees:

Forest:

I'd like to point out a couple of major differences between Islamic Law and US Law. For starters, our laws were created by man, not a fairytale Allah. I'd like to also point out that as such, we have not quite enough hubris to make our laws permanent, but Islam has no such qualms. The faulty 18th Ammendment was repealed after a paltry 13 years and our misguided Cannabis laws are changing for the better more and more each day. Islam however, has had a ban on alcohol for 1400 years. I think it's fair to say their prohibition on alcohol is written in stone. The real issue however isn't whether religious bans on intoxicants have any real world basis on whether they're harmful to the individual or society, the issue is whether religion has the right to create and enforce law, which I feel it doesn't.
With religious law you don't get to pick and choose the laws you think aren't that bad because they're based on something that transcends the religion, you get the whole package whether you like it or not.
Your post says to me that since intoxicants can be bad for you and Islam had recognised that, and that a year in jail is worse than a caning, that the logical conclusion is that the whole of Islamic law is therefore sane and acceptable, including brutal executions for things such as adultery.
Of course, the year in jail being worse than caning overlooks the fact that caning is a brutal affair that often results in permanent bodily damage, but to each his own I suppose.