Dr. Mario, Pichu, Young Link, and Roy were clones. I liked all of them, but their exclusion was logical. Mewtwo, however, I am still to this day upset about. Wolf, Lucas, and whoever the 3rd cut was make me a little bit annoyed because Lucas is the only Mother 3 representation and Wolf is a villain--something smash could always use more of. That said I'm not THAT bothered by their exclusion. What really bothers me is locking them behind a paywall, a shitty practice for shitty companies not named Nintendo.
Ice Climbers' exclusion will bother me just as much as Mewtwo's and I will probably never get over it. I didn't play them much, I certainly couldn't use them, but since Melee they've felt like an essential part of Smash and have always been a very unique character. Loss of Ice Climbers would be worse than Mewtwo if I didn't already love the shit out of Mewtwo due to his pokemon origins.
I don't see why you call this an overreaction. I'm upset at an unnecessary and random cut and the beginning of shitty practices rarely ever seen used by Nintendo. At least I'm not being petty about it and refusing to buy the game over this (like I know many already have and personally know some who will upon hearing this news). It's still smash, it still has a lot of characters I love and will be a blast to play, but it won't be the same without them. And if they are paywalled, I will pay through that fucking wall immediately though begrudgingly, because a smash roster without them isn't a smash roster I want to play with.