Rezzing is an underused mechanic in this game.
Most people will completely ignore dead players.
Some dead players would rather not wait for a rez and respawn as soon as they die also.
A solution to this would be to add an achievement for rezzing players. Frankly I'm surprised there isn't one.
Helping Hand Achievement: Rez 100 heroes.
I've Got Your Back Achievement: Rez 500 heroes.
Guardian Angel Title: Rez 1000 heroes.
Another solution to this would be to add a small buff to players who wait to be rezzed. Maybe they earn a small damage bonus or +1 Fighting for a short duration. To prevent exploiting this buff would have to be disabled for raids.
Bottom line is I'd love to see more folks out there engaged in helping one another and not just mindlessly droning for loot.
Let's reinforce community and a sense that all of our heroes are on the same team helping one another. It will go a long way towards promoting the game and the players within.