Some title sequences have to shoulder more story-telling load than others. Sometimes the premise is uncommon enough that very few viewers will understand it without help.
One of my favorite shows as an 8 year old boy was the Six Million Dollar Man, and the situation was pretty well-defined by the time the opening credits were over.
An astronaut flying an experimental plane crashes, nearly dies, and turns into a combination of Borg and secret agent through the creative use of after-market parts.
The Art of the Title has the details on how it all came together...40 years ago.