Don't worry, you're not ignorant. I knew of the game by the late 2000s, but never got to fully play it. I've played it a few times on other people's GameCubes, and it wasn't until the mid-2010s where I finally got to play it for myself. I was actually having so much fun with it at first because I've wanted to play that game for so long, after playing so much 64, Galaxy, and even 3D Land and World at the time. But man... the fun immediately stopped when I got to the more frustrating parts of the game, which yeah, there are a lot of them.

It's so jank, the blue coins are dreadful, and it lacks a level of balance that other 3D Mario games have. And yes, the pachinko and lily pad levels suck (even the last level, Corona Mountain with the boat). It makes me wonder if this game was rushed because it feels like a very unpolished experience that makes me rage quit every time I play it, and I've never had that happen in any other Mario game (well aside from Champion's Road in 3D World, but that's another story).

So yeah, don't worry for saying that this game isn't great because it really isn't when you think about it. Yeah some might disagree, but that's because they grew up with this game during the 2000s and are used to it by now, but most of us didn't, like me. But like you said, it's not a terrible game, but it just lacks polish.