Everything helps making the experience better. When I lvl on an alt and I group with someone, I keep in contact with some and help them by telling which quests are worth doing at x7, trade them surplus greens I make or find (no charge) and put up on AH cheap useful greens (usually from tailoring). On my Priest Zhaha I try to buff eveyone I pass... I miss a few :-( While this may seem like nothing big, if I make their stay on Kronos more pleasant (5-10) while lvling myself, I believe I done my part. If everyone did the same we should keep most. Though the biggest concern is world chat, it is toxic and will discourage many I'm sure.
/Zha