Eh, while yes I agree, the game has a looooot more items specifically designed to bash stuff on the head until it's dead that are majorly martial oriented, spellcasters aren't off as badly as you guys claim they are.

I finished the game once with an ice oriented silver dragon sorcerer (balanced difficulty, which I played mostly blind and didn't make the most powergamey decisions) and I am close to finishing the game again with a fire oriented red dragon sorcerer, but as a Dark Urge origin and on tactician, on my Durge I went a bit more powergamey with spell picks though.

Yes, high lvl spells are utter garbage, of all of them I very rarely use globe of invulnerability. Chain lightning sounds fun on paper (for something like storm sorcerer/storm cleric multiclass - which is next on my to-do list once the game gets some patches and maybe tactician is made a bit harder), but as it is implemented in the game it's utter garbage for anything that's not lightning damage oriented. Thing is, while martials are all fun and broken, I mostly use twinned haste on Jaheira (moon druid, myrmidon wild shape is more OP than any of the items you guys are complaining about) and Astarion (dual wielding hand xbows, yes, 2x hand xbows are stronger than the legendary longbow available in act 3) and use fireballs/scorching rays for days, hell on tactician my sorcerer Durge won duel against Orin in 1 round! All it took was 2 upcast scorching rays... My sorcerer can destroy most bosses with upcast scorching rays, it's pretty ridiculous, while also debuffing said enemies with radiating orbs and also dealing extra damage to illuminated targets thanks to callous glow ring. The 2 rings I am abusing are also available in act 2, so long before you get access to the end game broken legendaries. The only thing that stops spellcasters is imho spell slots, unironically. But since the game allows us to spam long rests with no consequences, well... it actually rewards us with more content for long resting often. Unless we're in act 3, which is long rest content starved at some point.

Could the game use more caster oriented items? Hell yes, especially boots. Should Larian nerf current legendaries/very rare items? Nah, just add more for variety.