@irontoenail - I agree with you in some ways, but I will still buy enhanced water occasionally. I reuse the bottles with tap water, because I do like to have some water onside in case I get thirsty.
The whole needing six glasses of water a day thing is a little bit of a myth. It includes water you get from eating and there is quite a lot of water in things like fruit for example.
But you should still stay hydrated, if you can and enhanced drinks can make drinking water more palatable to people who usually would only drink soda or coffee.
I think they should recycle the bottles. But aside from that I think it's your money, do what you like with it.