First, since in many fights aggro bounces between characters there needs to be some easily visible way to see who has aggro, perhaps a little text box with the name of the current aggro target for your target. That way in teams with no true tank people know who to bounce the boss away from during kiting.
My other suggestion is some kind of threat increase for bears or anyone wearing "tank" gear. Perhaps give swords (despite weak dmg) some taunt proc or maybe just increase threat generated by attacks. Something to make tanking more tanking and less for just beckon.
Just something to make aggro a real thing and not a game of tag with whoever does the most damage.