Not many of us are fast enough to move a foot the 6+ feet it will take to connect with an opponents head without them having plenty of time to get out of the way, or worse, grab hold of your leg. That's not a very comfortable position in which to find yourself :-)
This claim about having "plenty of time" to avoid or trap a kick is often made by those who have never trained in a kicking style. No particular knock on you, Jim, I'm sure you're repeating the words of others, but if that statement were true, don't you think no one would ever land a kick in karate kumite? Think about it: these are people who are used to kicks, who know a lot more about them than an aikidoka, who spend a lot of time trying to avoid or thwart kicking techniques...and they still get hit sometimes. If they
get hit, just what kind of time distortion trick is someone who isn't
experienced with kicks going to pull in order to have this mythical "plenty of time"?