A mentor system would be great, in my opinion.
Isn't the good feeling of having helped someone an incentive enough? Man, I wouldn't want someone to think I'm only helping them for my own benefit.
It was mentioned in another thread, that prestige points could be awarded with mentoring, which isn't a huge reward so it wouldn't make you feel as bad, I guess? xD
An idea I had, was to allow high level players to 'de-level' their character. This could be done simply by adding a debuff to the player, according to the level they wish to de-level to. If they de-level to 15 from 20, they would get as much XP from the Vault as they would from Ohdar Scar. Considering you keep your skills and talents, you would still be stronger than the average level 15. Which is not a bad thing, to be honest. So then a mentor could actually play with their disciple and show them things, rather than just doing things for them.
Another thing that could be done, is to use the 'Group XP' system, to a great extent. Where as, when in a group with your mentor / disciples, you could gain more bonuses. Better XP gain and loot drops, for example.
Otherwise, I support helping new players.
You are a child, until your dust is thrown to the wind. Living on, through the echoes of your life, in Humanities' mind.
We are the image of the invincible.