The main problem I have with this idea is that it would disproportionately screw over characters without good 50/50s.
As an example, let's say I'm using Kitana and you're on your last legs. All you have to do is crouch block - if I jump, or you see me go for b2, you just switch to stand block straight away. Effectively my only chance of eliminating that last 1% of health is by getting a lucky throw in.
Compare that to, say, Swarm Queen D'Vorah, who can relentlessly pressure with safe 50/50s and has an orders of magnitude higher chance of landing that last hit.
tl;dr No, it wouldn't benefit.