Good suggestion.
He is not suggesting for a removal of skillpoints to re-assign. He is suggesting that when you have (for example) 50 skill points to assign, you can start adding 30 to attack, but then decide that you only want to add 29 to attack and remove 1 skillpoint from attack BEFORE confirming.
Right now if you want to do this, you need to cancel ALL 30 skillpoints to re-assign 29. It's an inconvenience.
+1