Are you sure they aren't aluminum?

I think that part of it is plastic backlash, and partly that it's just this year's thing.

I personally felt that spending 10 or so dollars on one was ridiculous, given that they can make a coke can so cheaply that it's included as a throwaway with a soft drink. And sure enough, I found some in a dollar store, so I bought 3 matching ones to try them out. They're okay, seem to keep drinks cool for a reasonably long time. Mine has a screw top so it's not something you'd want to take on a ride unless you are willing to stop for a drink.