But how would that work?
- The system checks playtime on everyone and only gives loot to the one with the highest playtime? That would mean casuals would all quit, as they'd never get loot. It also means sitting AFK in Dalaran for days would improve your chance of loot.
- The system checks DPS on boss? It would reward the tunnelvision mage that stands in fire above the group player who actually interrupts and minimizes damage. And would it take gear into account, so scrub 810 isn't expected to do as much damage as mister 850+? And what happens when über player A has had bad drops and thus gets bad itemization, hindering DPS, while being every bit as good as someone else?
- How do you check whether healers and tanks did their part? No one died? What if the tunnelvision mage died? Not the tank's or healer's fault, but it would cost them loot?
There is no way to determine who 'deserves' loot more then anyone else and since we all pay the same, the solution is RNG. That way everyone has a chance on loot, but people WHO PLAY MORE have a higher chance of getting loot. Hey, see that? It already favors people who play more!