This is a common miss-conception with warriors. Warriors have nothing to do with health or ability to take damage or deal damage, but rather their overall team roll. Azmodan for example has more health than most non-buffed warriors and is a Specialist. He also has a lot of the damage mitigation talents that one would expect on Warriors. Sonya is a Warrior but is capable of Siege damage on-par or better than many Specialists (WoTB + Hammer build). She is also very squishy for a Warrior having less health than Li Li (a Support). A ranged warrior would work but it would require careful design. Imperius would likely have less health than Tyrael but instead deal more damage to compensate as well as some very powerful abilities with higher cooldown.