People leaving trials/dungeons after leveling should lose that XP.

[Maverick_Haas]

I think it's rather simple to set up rules.

Reasons you don't receive xp or items
- Leaving without a vote abandon

Reasons you do receive xp and items
- Vote abandon
- Vote kick
- Lockout
- Duty Complete

Sure, some people would then abuse the vote kick by afking, but it's less appealing to go for the vote kick than it is just to leave.
I think if you've got the inclination to waste everyone's time, you should have wasted your own.
It's not so much of a big deal if people are easily replaceable, but currently healers are in high demand and can take literally half an hour to replace.
It's not just a minor inconvenience, it's literally almost a whole hour of just waiting on queue times.