I was surprised to learn there is a worldwide escargot shortage. This does disappoint me since I like them, but it isn't as though the cruise line can do anything about it unless they start their own snail farm.
Johnny Rockets...RCI has charged the cover fee for several years. It isn't a new fee. I remember paying it in 2004 on the Mariner Of The Seas. When they first introduced Rockets on Voyager Of The Seas it was totally free but eventually it was shown that the teens aboard would take the place over as a hangout, and the paying passengers (their parents) had problems getting a booth. As Cruise Fanatic said, the charge was meant to be a way to discourage the hangout behavior.
On Allure the Johnny Rockets is in the Boardwalk neighborhood. They serve breakfast there too, and at least as of last year the breakfast did not have a cover charge so tips would be appreciated by the staff. The usual diner lunch menu food is complimentary - burgers, grilled cheese, tuna sandwich, hot dogs, and they stuff you automatically with endless plates of french fries and onion rings as soon as you sit down. They arrive steaming hot from the fryer and to me are probably the best part of eating there. Again, as CF said, there are items you have to pay for such as sodas (like anywhere else on the ship), and specialty items like the milkshakes and ice cream sundaes. But you can leave the place ready for a nap and not pay more than the cover charge. Enjoy!