USPSA and IDPA are both games.
They are different enough that they have different rules.
Typically, there are processes in place that provide avenues for changing the rules if the demand for those changes is strong enough. Realistically rules changes take time and are often not too huge in magnitude.
One of the great things about living in this country is our freedom of choice. If a shooter likes IDPA and USPSA, he can shoot in both disciplines. If he only likes one of them, he can shoot in that discipline. And if he doesn't like either of the disciplines, it is his right to choose to not participate.
It is my opinion that non-constructive criticism of any shooting sport creates a division among shooters who choose sides. And that division among shooters is something we CANNOT afford the let happen. We have enough naysayers and enemies of our sport and our Second Amendment rights. We don't need to help them.
YMMV