Your body has no real need for alcohol and can't synthesize it into anything it can use so why bother drinking at all?
- Because there are known health benefits to drinking in moderation
- To be social
- Because it can make you feel good
- Because you enjoy the taste
- etc etc
Your body has no real need for pizza or steak or desserts or TV or sex or a zillion other things either. So? If you only have or do things which your body really needs, you're missing out on a lot of enjoyable stuff. Alcohol only stands a real chance of harming you if you overdo it, like most things.