The biggest travesty with tank self-sustain is that it doesn't even create interesting gameplay. What makes lifesteal meaningful in games is the potential to fail, and fighting tooth and claw to survive. You need tight restrictions on self-healing and limited resources to keep yourself up. It can't be available on demand and shouldn't keep you up indefinitely in the absence of a healer.

One way of achieving this is through making self-heals be dependent on timing and context (i.e. potential lifesteal gated by the amount of damage received in the past X seconds - Death Strike from Warcraft is the classic example). Implemented correctly, lifesteal can create opportunities for tanks to demonstrate skilled play and pull off memorable clutch saves. This game just doesn't pull it off, sadly.

What the game designers have done instead is simply create self-regenerating tanks that can heal themselves up on demand whenever they get scared. WAR's current design primarily caters to the sort of tank main that can't tolerate their HP dropping below 80% and demands that their healer constantly be healing them. I don't think any self-respecting tank wants this. The dev team really need to re-think their approach to the role.