I do not own a Glock, but take apart and clean all magazines every time the gun is cleaned. Do you have to? No. But you would not change your oil w/o changing the filter would you? Maybe not the best analogy, but crap gets everywhere, clean the crap out. It is too easy to not do it.
In life, strive to take the high road....It offers a better field of fire.
"Robo is right" Fuzzball