This is exactly what I'm talking about. The cartwheel kick would appear to be bad if you have poor balance, poor aim, haven't practiced on a bag, or don't know how to set it up. Any of those possibilities will derail that cartwheel kick, and result in you whiffing on the kick, getting kneed in the face while you throw the kick, or getting your arm broken.
That doesn't mean the cartwheel kick is bad. It just means the cartwheel kick has requirements in order to be used properly. If used by someone skilled in the kick, in the right situation, it's a good technique. If used by someone unskilled in the technique, whether the execution or the strategy of the technique, then it is a bad technique.