The BG3 loot system is a bit more realistic than that one in WL3, but I sure wouldn't mind if Larian adopted group looting and switched to a shared party inventory. I would personally trade away some immersion for less busy work in inventory screens.
A shared party inventory would be GREAT. I mean, we can already equip items from other characters' inventories, instantly send items between characters over any distance, eat food directly out of other characters' inventories.
The only reason I can think of for them not having group inventory is multiplayer. In multiplayer, a lot of people probably want to have their own separate inventory.
But maybe they could set it as an option. Group inventory defaults to 'on' in singleplayer, and individual defaults to 'on' in multiplayer. That seems like it would be the best.