My argument isn't that healers don't need to be geared, it's that healers aren't so much more important than the DPS classes that items that equally benefit both necessarily have to go to the healers out of hand. A certain amount of healing output is a minimum requirement for handling an encounter, but once you've hit that you're golden; the only question becomes how long it needs to be sustained versus how long it can be sustained. At that point, there isn't much functional difference between higher dps and raw endurance, except the former has the advantage of helping the raid to beat enrage timers, bull through tough phases, quickly take down adds and to make raids shorter in general.
Honestly, I liked how my old guild handled it best, since it was basically classic compromise situation. The roster was basically set in stone and the vast majority of items basically went to whatever class benefited from the item the most with little prejudice as to class role. The only thing that we were adamant on was tier tokens, in which case set bonuses often acted as a sort of tiebreaker along with what alternatives would theoretically be soon available. Basically, if you've got a single piece of tier six and your class has a sweet two piece set bonus, then I'm afraid everyone else is probably SOL when another tier 6 token you're capable of using drops. Likewise if you're not going to use something right away because it'd break up a particularly sweet lower tier set bonus, than I'm afraid you're going to have to get back in line for a while regardless of how nice of a guy you are. For example, rogues tended to be favored over mages and resto druids in terms of tier 6 tokens because frankly, the druid & mage set bonuses were kind of stinky, 4 piece mage bonus aside. In exchange the other two were slightly favored when going after best-in-slot non-token drops. The only role that was really favored were the tanks, and even then that usually took care of itself, tokens aside. Even then the implications of the 4 piece Gronnstalker set gave people some pause.