High HP is a gimmick. one-shot attacks are gimmicks. AoE knockback into lava is a gimmick. AoE pull and spin-to-win (Kholer) is a gimmick. The trick is knowing the enemy and realizing that you DO have the skills necessary to counter it. But apparently it's too much effort to step away from the comfort zone of those specific 10 skills you always run in order to bring the support skills and run the weapons with the proper skills needed to survive and win.
I understand it. It took me a long time to muster up the courage to pick up the daggers and face some legendary bosses at close-melee range because that's how it just needed to be done, due to "gimmicks". But that's something that needs to be done. Adaptation is key to survival in all situations, even a video game.
Well there's your problem right there.
HP resembles... well, their HP. What do you expect? A giant rock monster to have the same resistance to swords as a human? Nope.
AOE knock-backs? What do you think would happen, that you would happily absorb a giant explosion in front of you and keep walking forward? Keep dreaming.
I get where you are coming from, but let's face the facts. ArenaNet is a multi million dollar industry, they're not going to corrupt their combat system. As far as I am concerned, I am perfectly happy with it & they made it correctly.
But invulnerability? Sure. If a monster that is basically born in a magical realm and able to use their powers to protect themselves, Fine with me. Magic doesn't last forever, you'll be able to kill it eventually.