more often than not, they’ll be “busting out the pitch correction”— as you’ve said— because they’re forcing the group to hit notes that aren’t in their range, which may lose the member’s own color

Bingo. This is my pet peeve with autotune, it makes people end up sounding the same. Like, you could probably replace the idol with someone else and most people wouldn’t even notice the difference.

If the vocals aren’t interesting then the instrumentals are probably carrying the song, which isn’t a bad thing, but it says more about liking the song for the instrumentals more than for the vocals.

Another counter argument to OP’s position is that, on the contrary, having skilled vocalists can expand on what the producers can do with a song. OP is assuming producers push idols to sing in more dynamic ways when they suck at singing, but one could also argue that producers push idols to sing in more dynamic ways when they know the vocalists are excellent and can do more with their voices if these vocalists also have wider ranges. So OP’s argument is also a two-way street.