This was only put into place so people couldn't roll on gear for their offspec and win over someone who needed if for their mainspec. A rogue needs leather for their mainspec just as much as the druid tank needs it for their mainspec nothing wrong with this at all. Just because you tank something and may put in more work depending on the boss doesn't mean you should get priority on all loot.
Im defiantly not saying its unfair, in reference from druids to rogues. Just pointing out that the system is skewed in favor of plate tanks. Plate tanks will have a 50% or 100% at getting their loot drops. So there is incentive for plate tanks to tank LFR with the much higher chance at loot, whereas there is no incentive for ferals to tank LFR.