Mainly it was where thrash was born, but there were other great acts too. Besides a lot of big name thrash acts like Exodus, Possessed, Testament, Metallica, Megadeath, etc., Primus formed out of the ruins of Blind Illusion, the Dead Kennedys got their start, and Faith No More was founded.
I'd still rather go back to LA in the mid 80s to see RHCP, Jane's Addiction, Fishbone, and others but that's just me...