The only sensible reason I can think of to dislike Steam is that your games are tied to your account, so if you lose your account, you lose your games. But that can be easily rectified by:
1. Keeping your account information in a safe place.
2. Not doing anything ban-worthy.
Really, if you can think of a better (realistic) way to stop piracy, I'd like to hear it. Seriously, I'm all ears.