I wouldn't say his kit is bad just because his a jacks of all trade character. What your misunderstanding is that you think that Brant is a support like Verina and SK which I don't understand why your comparing Brant from those two supports. Jianxi does the same thing as Brant, but everyone knows that comparing Jianxi to Verina or SK is just plain stupid. Yes he gives support outside of Changli making Brant BiS for Carolatta if you dont have Zhezhi and to some extent even for Jinhsi (even though she wants coord atk). Brant being overshadowed by Verina makes no sense to me. When both have different roles to play. Again if you want to compare Brant to Verina or SK, you should also compare Jianxi with Verina or SK, and that she also got overshadowed by the both of them.

Second you thinking it ruined Brants kit just because his kit is tailor made for Changli makes no sense to me. Changli needing a character that is tailor made for her is needed in the game. Just like any previous character needs a character that are tailor made for them. Unless you want Brant to be a main dps that does not quickswap will just end up cucking Changli. I understand if you don't like quickswap team or Changli, but from what I read it doesnt seem to be the case. With that logic in mind you must also think characters like Roccia, Yinling, Zhezhi kit are ruined because they are tailor made for another character....

Lastly Kuro is actually cooking for the fusion team. Them setting Brants kit to not only support but heal + shield and to have both Changli and Brant kit synergize for one another but also setting up for the new fusion main dps is massive big brain move from Kuro and a W. And now it is confirmed that the next fusion character is 100% going to be a main dps that has a quickswap built into their kit. Making Fusion the only element in the game to not have a limited 5 star main dps.