There really isn't much wrong with Winfurae's argument. If you have few warrior tanks and if you have few Feral Druids and if you have a Retribution Paladin to go with your Rogues and DPS Warrior and enhancement shaman, then of course the Feral Druid is likely to see a lot more Tanking than he will DPS.
Interestingly, in my guild it is much the reverse as we have 3 warrior tanks and 3 feral druids and 0 retribution paladins (5 holy paladins though!) to go with our rogues and dps warrior and enhancement shaman. We also have 4 Hunters that turn up a lot. So quite often we'd have 2 warrior tanks before any druid is called to tank. We usually have 2 physical dps groups. One with 2-3 rogues, dps warrior, enh shaman and 0-1 feral druids and one with 3 hunters, a resto shaman and a feral druid. With 2 Prot Warriors in for trash and any fight that requires more than 1 tank, the Ferals really don't do that much tanking. Furthermore, quite a bit of tanking druid loot is also great dps loot. So in our guild, it was decided to treat Druids as DPS that can tank when a 3rd tank is required.
Basically, a loot distribution solution that makes sense in Winfurae's guild does not work in ours. And that's as it should be. One solution does not fit all. Whether it's because of class composition, player attendance, player skill or just what loot dropped when, the right answer for any given drop is not going to be the same from one raid team to the next.
Do what is best to avoid drama. If the drama caused by new rules meant to optimize raid DPS causes you to have to replace a member with an initiate with 100 less DPS, you probably hurt progression overall. If the drama causes people to be less enthusiastic to raid, you may get poorer attendance which causes new item upgrades to be spread over more people, meaning you have to farm longer for every bit of improvement-- again, hurting progression overall.
Manage your guild members first, and get them to all consider what's best for the guild. A druid taking two, three, five pieces of gear from rogues isn't a big deal for overall raid DPS; but keeping everyone involved happy probably is.
I have not seen the point made that very rarely are contested items such as the ones mentioned being fought over by people with equal seniority in the guild. If your guild is lucky and has had little to no turnover, especially after Illidan is dead, then I am envious. I am in fact a paladin tank. I will be looting the next Tempest my guild sees. There are a couple casters that still need one, however all the more senior casters that care to use the sword have one at this point. The only casters without it are our newer members/apps. Some of them joined months after I was exalted with Hyjal. I've been giving 90%+ attendence since SSC. If I were made to pass the weapon to these vastly newer casters I would not have to say a word in my defense as the more veteran members in the guild would hang our leadership for me. Would people have been upset with me looting the very first one? Who knows as I obviously did not push to find out. I'd imagine that taking the sword over casters that had higher seniority over me would have been dumb. Things such as this cannot be accounted for, yet come into play. As such each guild will have their own internal way of handling such issues even if DKP says otherwise.
Our guild actually has a interesting way of handling feral loot. We get each feral to declare a spec for themselves, either cat or bear. Obviously we make sure that not all ferals are cats and not all are bears, there needs to be a mix. The cats have priority on dps gear just as a rogue does and bears have tanking gear priority. Both are expected to acquire and maintain the best sets they can for both roles and perform both roles as needed, but this allows them to go after the loot they are personally interested in without creating conflicts. We tend to get our bear spec druids to tank first over the cats, but when we need 4-5 tanks the cats obviously put on their tanking gear.
This system isn't optimized for progression since the cats do take drops from rogues sometimes and bears from prot wars/pals, but the impact is extremely minimal. More importantly, everyone is happy. The ferals can get the loot they are interested in, and no one feels one person gets all (or none) of the loot. Our feeling is that when everyone in the raid can ask for a roughly equal amount of loot of the type that they want overall people will be happier. We could be very restrictive in deciding who gets what to try to maximize our dps/healing/whatever but happy raiders who feel that they can get the items they want and save up if there is one thing in particular make for a better time.
All this said, I think it is very reasonable to say that if an item is best in slot for someone no one is allowed to take it over them unless it is also best in slot for that person.