There have been some surprisingly insightful posts on reddit regarding their strategy. They made the launch characters so good, that they are worried about running themselves into a hole. You can see it a lot with characters like Yoimiya, Kokomi, and Sara. They're all worse characters than what came before them with increasingly obtuse mechanics because they want to differentiate them from the launch characters, but not make them as universally good. This is a big problem for players because it means that new characters will always have something neutering their kits so they aren't "too good" anymore. Yoimiya has strong ST damage, but no AoE at all(despite shooting exploding arrows), and she cannot make use of her own Burst at all, forcing you to switch to a subDPS. Kokomi has -100% crit so you can't do big dick vapes all day, and her whole kit revolves her being up for only 10 seconds during her burst, then fucking off until it's ready again. BUT - her DPS is so much worse due to no crits, that there's no benefit to using her for those 10 seconds when you could just pop Barbie's ring and switch back to Klee and keep fucking shit up. Sara is pretty obvious, but she's a pocket buffer for Shogun's burst, and that's it. Not even for Shogun in general, just her burst, because shogun does no Electro damage on her own (her skill is independent for her) without the burst, and the buff only lasting 6 seconds....which is like 2-3 seconds short from the entire duration of Shogun's burst to begin with, because it lasts 7 seconds, there's 1-2 seconds for character swap, and it doesn't snapshot for some reason.
Even Ayaka was built with neutering reverse melt in mind. Her attacks happen so quickly and "overwrite" pyro effect so instead of one massive damage reaction hit like Mona, you get 30 little hits and only 1-2 of them actually invoke Melt.
It's a big problem if they keep developing characters this way, because it's only going to get worse and more limiting. They probably see it as a good angle for them, since characters only working with certain other characters supposedly gives people a reason to keep pulling new characters. In truth, though, it's just going to lead to people not pulling and continuing to use Benny/Xingqiu/Xiangling on every fucking team from now until the game ends.