(note: not a game designer - or even on gameplay, but i AM an ex-plat 5, currently-hardstuck-gold-5 brand one trick)

brand's ult gets wrecked by morg/malz/yasuo/braum, and he becomes less than useless if the latter two sit on their shields until they see the ult coming. i often spend so long waiting for the perfect bounce in a teamfight that i occasionally die too fast to use it.

i guess the other option would be to make the ult whiff when he dies, but to counteract that it would have to bounce much faster, do more damage, or maybe apply multiple burn stacks. idk, i do kinda agree that brand's ult feels uncounterable if he gets even a little ahead, but also one 300IQ player can move out of the teamfight to severely reduce his damage output. in lane, though, i think he's super oppressive and gross, and if he makes you go b at all, he can clear waves so fast that you're gonna lose a lot of ground.

not sure making it a skillshot would be any more effective, cos it'd still hit something in a teamfight pretty easily and to not be truly terrible it'd need to prioritise champs