I've heard rumors (somthing on wow radio i think) that blizz were either considering or had at one time considered changing the drops system to apply more to the group that were in the instance, e.g. if no plate wearers in grp, plate wouldn't drop etc.

Dunno if it was something that was considered and discareded, or might one day come into effect. I'd love to see this happen, along with the much discussed potential sharing of rep across characters on an account.