Spells need concentration for the game to be balanced. If for example clerics could concentrate on multiple protection/buff spells at once they would be extremely overpowered. The action economy needs to make sense, and being able to fling all kinds of spells willy nilly while taking a bunch of hits, breaks that. Magic isn't supposed to be effortless.
Now I do think that in BG3, a lot of spells are buggy or badly implemented with regards to how their concentration works, but it's fixable. Removing concentration, a core spellcasting mechanic, is not going to happen. Making it more stable, however, is doable.
