@Sano
Something you might forget, or just haven't experienced, but i think a lot of boxer or even kick boxer don't realize. Slipping punches is not dangerous only against kicks. Of course if you are in a low stance, and make big movements it is a big factor.
But also a light slip to the side to avoid a punch, is a dangerous move, because: elbows.
Its not that hard to make your missed punch into an elbow, or just set it up as a feint to an elbow...You cannot slip an elbow, the surface is too big.
Can you pull that move every now and then? Sure... Can some fighters use it more often, yes, some exceptional fighters... but there is a reason why in MT, slipping punches to the side is not a main defensive option...
There are lots of problem with it, from kicks and knees to the head from an excessive movement, to be unbalanced when your opponent grabs you into a MT clinch after a missing punch, while his hand is behind your head, in an optimum position, to elbows...
If you slip to the inside, i 'll go for a double MT clinch, if you slip to the outside, i will push you further down to unbalance you into a knee (i think that's what happened in the sparring boxing video of Connor with the guy he "supposedly" floored, without the knee obviously), or just turn my punch into an elbow...
I don't remember what experience you have in MT, but i am sure if you had pro matches with elbows, you would see/understand why it's not that simple.