It's been proven time and time again that the best form of (Cheap WoW Gold)damage mitigation is to not be hit at all. For as long as paladin tanks choose to favour damage reduction (instead of avoidance) they will never be viable main tanks, simply because they're always on the edge of being 3-shotted (Personal experience there.

Tanked Maulgar once upon a time, I didn't dodge or parry an attack for 2 hits, just blocked, and arcing blow 1-shotted the rest of my 18k health down before the healers could do a thing. Warriors would have had a much easier time as they could have used last stand or their lifegiving gem or to a lesser extent their shield wall - But it is simply more likely that a warrior is capable of focusing on avoidance and would have completely evaded at least one of the attacks - While still having enough stamina and mitigation to have most likely taken the damage and still lived.

Trash is the last place where healers are concerned about (WoW Gold)mana. As a prot paladin I'll happily spam-heal 3 mages AoEing down a pack of 3 trash if we save time compared to me tanking one and single-target DPS burning it down. Similarly, trash is where the threat really counts - On bosses people will conserve their DPS so they don't spend half the battle wanding, on trash it's free for all and the first person to pull aggro wins. 

If you don't have mana problems, you're taking too much damage. You've done the easymode of Karazhan like anyone else. Up to Curator can be tanked with 10k unbuffed warrior - Shade of Aran doesn't require a tank at all because you can just take 8 dps and 2 healers, kill him before the first evocate and easymode. When you get to Maulgar and Gruul, or even to Nightbane and Prince in Kara - Your healers will really feel it the pressure of you not dodging.

I believed I could maintank once-upon-a-time too, but it is a pipe dream as it stands for horde paladins and a minor possibility for alliance. While you can tank in a casual guild, once it gets to progression you just will not cut it. As it stands there are no +spelldamage +resistance +stamina items out there, meaning you won't be able to tank resistance-based encounters any better than a warrior. And there are an awful lot of (WoW Gold)them after Kara. You take more damage than a warrior, more often and on bosses you may out-aggro a warrior, but as I have repeated in the past: It doesn't matter how much you out-aggro the warrior, if the warrior still out-aggros the DPS.