The $2 soft drink access fee doesn't bother me much, but I think if US would have thought out this al a carte program a little bit, it could have been released as a real positive, and still accomplished the same thing.
Say, water is free, soft drinks $2 charge, maybe vita waters for $3, Doritos, Fritos, Potato Chips, Peanuts for $2...
The part about US that really annoys me is that if they would just think things through a bit more from the customer perspective, they could release a program that would generate more revenue, and wouldnt annoy people so much. They could position it as, "we now offer all these great choices" vs. lets punish our customers by charging for something that was once free - without any enhancement.
Successful marketing is all about packaging. Just improving something slightly makes charging for it less likely to annoy people.
Amtrak also has a much better system. I doubt the Flight Attendants would have a hard time selling things if it was done like Amtrak. They'd have a little snack bar in the galley with a cash register and people would get up when they are thirsty and come get their own stuff...