We train to defend against kicks at my dojo on a regular basis. Maegeri and Yokogeri are the two kicks we concentrate on the most.
When we practice these techniques, the students are taught to keep their "guard" up when performing the kicks.
Kicking is a rather common attack, this is why we incorporate techniques against kicks into our training.
My wife and I attended the 25th Anniversary Seminar with Koichi Kashiwaya Sensei at the Rocky Mountain Ki Society Dojo in Boulder, CO a few weeks ago. Kashiwaya Sensei stated that often a kick may be combined with another type of attack, such as Ryotedori. We practiced performing Ryotedori Tenchinage in comination with Uke kicking. In this case, the execution of Tenchinage involved using a leg sweep.