... I prefer to refer people to the authority on the subject:
https://imgs.xkcd.com/comics/password_strength.png
There is no reason for 'requiring' those strange combinations of upper-case letters and numerals and symbols, just in the (mathematically incorrect) sense that they 'feel' more comfortable. Long passwords, by contrast, are far more secure, even if they are composed exclusively of dictionary words.
Information theory FTW!