Here is the thing, the only thing WAR really has going for it right now is the ability to mitigate a big hit after taking it with Inner Beast.

If I take a 4500 dmg mountain buster + 900 dmg AA, I need ~3000-4000 healing before the tumults start. I'm not worried about overhealing in such a situation. I'm worried about not dying. Even if both healers drop perfectly timed cure II's for 1500 each, that still leaves me at a significant deficit, which is largely mitigated by Inner Beast.

If Inner Beast were changed into a HoT, it would be straight up horrible because you wouldn't have the burst mitigation. It would net slight efficiency returns for healers, but it would leave WAR without any tools to deal with big spikes of damage unless it was something obscene like 900% damage is returned as health over 15 seconds, at which point it would tick for ~700 which would possibly be enough, but that would probably be far too efficient and extremely OP.

It would also mean our peak burst mitigation would be way down, as it would negate the use of IB -> Infuriate -> IB.

In the end, the better way to avoid over healing would be to make Inner Beast an absorb shield instead of a heal. But that's neither here nor there. There are a hundred things SE could do to close the gap. It just looks like they aren't interested in doing any of them.