Well there are 3 reasons:
1) The HUGE addition to Fan-Service. The first season had it and it was enjoyable. it added to the atmosphere and made some moments quite humorous. However, in Return of Kings, you can be in the middle of watching the most intense fight scene ever and suddenly you have breasts jiggling in your face. I'm talk about Dead or Alive Extreme Beach Volleyball level of jiggle physics
2) The animators tried too hard. Like, the first season was perfectly fine and I still praise its animation. However, there were lots of moments in this season where things felt disjointed and forced animation-wise.
3) Nothing really happens. Sure you have a major conflict and the opening sequence is a joy to watch, but for a majority of the season, it's just...boring. The end really redeemed it, but still, the show didn't provide as well as it could have.
That being said, the season was still K. Beautiful style, great music, fun characters, cool concept. It just was not executed nearly as well as with the first season. In my honest opinion, Return of Kings in one word is unnecessary. They really should have just ended the show at the last episode of season one and been done with it. Season two, while still enjoyable to anyone who watched the first season, is a slight let down. However, I still very much enjoy this show and recommend you watch it if you have seen the first season. You have nothing to lose
And that's why K: Return of Kings gets an 8/10
