I’m not seeing the same person twice much on Classic.
I do think chat is more positive. The toxic chat is there, sure, but there’s also a level of helpful chat with people asking how to complete quests and others answering, and sometimes grouping up.
Typically that doesn’t happen in Retail because all the quest objectives are marked on the minimap anyway, and grouping up makes them slower rather than faster. I do see helpful chat on war mode shards when assaults are on, warning of where the enemy faction is and such.
Taking the quest objective markers out of the game and making world content a bit more challenging - and unscaled - would probably help a lot when a new expansion releases and people are leveling.