*promoting* the music. if you still couldnt understand, example:
linkinpark videos, the music may or may not appeal you, be it good or bad, their 3DCG (say, point of authority) or animation (breaking the habit) does provide an attraction that will beckon/keep you on watching it, and thus at the same time, you listen to the music. which is the main purpose/point of having a music video or more specifically, promotional video, to PROMOTE the music.

war has no need for andrei smirnov

theres atleast 3 ppl that is interested in Setsuna.
Marina, Nina, and .... ? 

all this while i've been skipping the music intro for the 2nd season, now i realize, why's tieria battling with ali in the intro?  ghay?