It's getting better, I see people asking specifically for protection paladins for instances, as more and more people realize that they are the superior tanks for doing that stuff. People who put down protection paladins in trade chat more often than not are put in their place by everyone else calling them an idiot. And I am met with rejoice instead of pessimism when I join a party to tank now.
No one likes getting chided for their choices, but if you know it's the right one, and can argue it and fight it back then you shouldn't feel bad for it. The idiot's who say stuff like that are really just that, idiots. And it doesn't take any extra effort at all to prove them wrong, that's the beauty of the thing. Just do what you normally do and let your actions speak for themselves.