The grammar offered an irresistible linguistic challenge. Klingon is difficult but not impossible, weird yet totally believable. Anyone can put on a pair of pointed ears or memorize some lines of dialogue, but learning to speak Klingon requires genuine hard work.

Most languages created for fictional worlds involve simple vocabulary substitutions, such as moodge for man in A Clockwork Orange, or meaningless streams of noise, like the high-pitched jabbering of the Ewoks in Return of the Jedi.
Klingon is something altogether different. There is a logic behind it;
a linguist doing field research among Klingon speakers would be able to
work out the system and describe it as he would an exotic indigenous
tongue. — Arika Okrent, Slate