I agree with your statement that legendary tier champions should be a nice reward for dedicated players who put in the work and money to obtain them. That said, I'm not sure I would agree that there are bad legendaries. One of the nice things about this game is the amount of thought put into the balance of the champs. Almost every champ can find some utility somewhere. If you gear/master them correctly, they can all fill a slot on a team. There are several content creators saying this and doing videos to prove it. Part of the problem is that people get too obsessed with tier lists and think they need to chase 4 or 5 specific legendaries. This idea needs to die. They really need to work on their team composition skills. No legendary is going to save you from bad team composition. They might make it easier to access certain levels of dungeon, but ultimately a good player can build a complementary team with lower-tier legendaries. Conversely, a team of supposed SS-tier champs who aren't skilled/geared correctly can wipe on a relatively low level dungeon if they don't have the right roles filled.