I think that encapsulates the unhappiness perception. Vintage frequently doesn't feel like the vintage we're used to playing.
I agree entirely, but don't forget that "the vintage we're used to playing" is pretty ambiguous. I got into the format around 17 years ago, and back then there were plenty of players who were upset that their 5-color Keeper control decks couldn't keep pace with the bleeding-edge new style of play brought about by Fetchlands and Quirion Dryad. The game is constantly changing year over year, and almost by definition you're going to love the version of the Vintage that people played when you first became passionate about it (because if you didn't love it, you never would have gotten hooked). So almost by definition, as it changes you're going to run into patches where you enjoy it less than you used to. People tend to interpret this as a steady decline from some golden age, but it seems more like a sampling problem to me.