I feel like the only alt friendly addition that I think they could/should add is making temporary event unlocks account wide. Particularly for crossover events where there's no guarantee the items will over be obtainable again. Perhaps as a step further, make achievements account wide.

That said, aside from RPers and hardcore raiders, I don't get why a lot of people have alts in this game. I've put in hundreds of hours on one character and I still have a ton of stuff to do. The idea of an alt is completely a nonstarter.