Baxter Humby makes good use of the side-kick actually. Always interesting to see. He's one tough Indian.
I'm not saying the kick isn't awesome when it lands, just that it rarely DOES land and when you miss with these kicks you're typically left in a bad position and have just used a huge amount of effort to do a kick that didn't land.
I have a fair amount of faith in the spinning back kick provided it has a proper setup. (I like jab-cross-jab-spinning back kick. This being a completely distinct statement from "I've had tons of success with... .") But there's this very insidious myth in martial arts that techniques that are harder to perform are, consequently, more valuable. If it's harder to do, it must hit harder. Or faster. Or more often. That simply isn't true. Yet it's so hardwired into most martial arts curricula that we take it for granted. "You've learned how to throw a decent round kick, so let's go ahead and learn the jumping variation." I have no regrets about having started in taekwondo. And I think that, mechanically, it still has a lot to offer. But I think its stylists need to be very careful about not giving up the ability to question certain basic assumptions. I think that's true across the board though.
Yeah it needs a set up as it is hard to land especially against a fighter with good eyes,I always used it at close range and of a left hook to the body and with a small jump,depends to what type of fighter your using it against as to what set up you need of course. The danger as MB said is the position it leaves you in if you miss,but then some European fighters in Muay Thai leave themselves wide open to counters even when round kicking. I found years ago that i you work it and work it and work it somemore it can be your ace in the hole that one day you can pull out the win with