kungfu often has a bad rap. but its kungfu's own fault.
there are too many charlitans and frauds in the world of cma, and the biggest names in ma will be the first to point that out. serious negative pr for the cma.
another theory i have regards modern wushu schools. modern wushu is very, very difficult to do, takes immense amount of time, energy and effort to excell in. Most people who are into martial arts, after a bit of time in a school that is handing out wushu material will often times veer away from that because they are seeking fighting skills, and eventually realize their time could be better spent, well, fighting.
This can often leave a very bad taste in someones mouth, sometimes making them switch to an entirely different style. MMA, Boxing, Thai, BJJ, etc. all very popular MA's with good rep and outstanding viewable credentials.
a couple of my thoughts on this one.
For whoso comes amongst many shall one day find that no one man is by so far the mightiest of all.