It wasn't supposed to be a nerf, it was to reverse the INSTANT Ready activation from January. However SE says they made all Ready moves 60 frames/1sec activation ....if some went from 30 frames to 60 frames, I'd like to know ...but I don't think that's the case. Foot Kick was always a slight delay in activation.
You're right there was a delay but it's even much more delayed then it used to be.
As in usually when I fire off a Foot Kick when I'm near a mob, it usually hits the mob before it bothers to hit me. Now I'm using it and the mob hits me
before Foot Kick/Whirl Claws go off. So yeah there was some delay on Ready moves but it seems the devs just did a lazy blanket covering of code without bothering to look back at what the delay was on some mobs over others.