Haha, I know EXACTLY why…
“- While performing Light, Medium, Heavy Spinning Bird Kick Chun-Li will now be knocked down if hit.”
…has become…
“Light spinning bird kick now causes knockdown; damage reduced by 60 (160 → 100); recovery reduced by 2F (12F → 10F); stun reduced by 80 (180 → 100)
Heavy spinning bird kick total damage increased by 10 (200 → 210); now causes knockdown on hit; (recovery increased by 4F (12F → 16F)”
It isn’t because of mk sbk to super, and not just that making non-ex sbk knock down leaves the opponent in a limited juggle state, but much more specifically, it allowed non-ex sbk to ex legs in the corner.
j HK, cl st HP xx hk SBK - 350 damage
j HK cl st HP xx hk SBK, ex legs - 462 damage on Cammy
j HK, cl st HP xx hk SBK, ex legs, ex SBK - 563 damage on Cammy
j HK, cl st HP xx hk SBK, ex legs, U2 - 620 damage (depending)
hk SBK to ex legs was rather character specific (Dhalsim, Boxer, Claw, Viper, Gouken, Cammy, Rose, Hawk, DeeJay) and hard to do as you frequently need the sbk to hit exactly right and then get ex legs out on the earliest frame. By using mk SBK, you didn’t lose much damage and you got an easier to perform combo that worked on everyone but Blanka, Rufus, El Fuerte, Akuma, Ibuki, and Oni. There are bunch of ways to apply this including after a focus crumple, and they all did a hefty chunk of damage for only a little meter.
At its silliest, you got:
CH nj HP, cl st HP xx hk SBK, ex legs, ex SBK stun nj HP, U1 - 801 damage on Cammy
But now only lk sbk to ex legs will work, with reduced damage and stun.