Yeah! Why did they unfairly screw over the best tank in the game to help out the other ones?! Those jerks!

Okay, but in all seriousness? All three tanks do the same job and require the same tools to do it. Unless you'd rather them have gone a different route and take provoke away from everyone but PLD? That'd make them unique still right? Yes, but it would be poor design since everyone needs that tool. Same thing where DRK is concerned. Sorry mate, but there has to be some level of balance. They still each play their own ways.