Until they nerf the hell out of modifiers making them non-relevant, the issue is very simple: the ratio between EHP pool and player damage. Given how damage multipliers scale up way faster than EHP ones for any character/build i'm seeing around everyone strives for as big as possible EHP pools while mantaining high damage.
So you end with very high damage and a relatively small EHP. Thus even if reflect mechanics only take in consideration a small % of your damage, still it's way above your EHP. Anyway nerfing the reflect multiplier or making it consider less of your total damage would make them irrelevant, as again nearly any build goes leech, which again scales with your damage and not the EHP. This means that nerfing it would just make leech relatively more powerul to the point reflect can be ignored as you'll end healing yourself for more than the reflected damage.
They should also nerf leech at this point, but then you're taking out the most effective healing in game without any real reliable fallback.