Of course it isn't. It's just that, as a value judgment, saying "the game is perfectly fine because it's popular" can come off as intending to say "this discussion is over". And there's no reason for that- any system can be improved, and I think it's worth looking at ways it can be, and to find pitfalls that are created if you change the wrong parameters.
So having a discussion about the game and saying "I don't like this/it doesn't feel right to me" in the hopes of discovering whether or not things can be improved or if you really should leave it alone has value, at least to me.
"It's making money people play it, so it's obviously fine" has no value to me. Like, I get that, obviously, or we wouldn't be talking about the game. But why should I just take that as gospel, when I and others can find the truth on our own?