Gripes about expanded playoffs all depend on what you’re griping about.
In the NBA as mentioned, you normally have a clear gap between the 1 and 8 seed and the 5% chance or whatever that the 8 seed has isn’t worth playing the games.
The two playoff teams with the worst records are Jays and Astros. Both have more than a punchers chance to win their respective series. So in that sense, there’s nothing out of place in terms of quality of play/games.
So I think gripes in baseball would be more limited to traditionalism, being adverse to “everyone gets a trophy” culture, and principle