This is one of the things that I think modern MMORPGs get wrong. They listen to people complain about stuff like squishy tanks pets, and they adjust the class to make the pets less squishy. What they fail to take in to account is that the fact that the pet is squishy is offset by the skill of the player to utilize the pet to its full potential and make decisions that are best for each encounter. That's what makes the games fun.
When you start normalizing everything, balancing classes, and making the fights more predictable, you take damn near all of the fun out of the game.