"[somebody]'s theme" vs "[somebody] theme" — Saxon genitive dillema

I wouldn't think of it as "eliding" anything: there are two different constructions:

possessive + noun

modifying-noun + noun

The first is mostly limited to animate possessors, and denotes something belonging to or specifically associated with the possessor, whereas the second is not so limited, and denotes a less specific association.

In the cases you have given, either is possible*, with little or no difference in meaning. But sometimes one is impossible, or there is a difference in meaning. So

007 theme

Means a theme associated with the idea or the person 007, whereas

007's theme

is specifically thinking of 007 as a designation of a person, and specifying a theme associated with that person. Similarly

James Bond theme

is ambiguous as to whether it means a theme specifically associated with the character of Bond, or more generally associated with the phenomenon (or brand) James Bond.

*At first I didn't think "007's theme" was possible, until I remembered that "007" can refer to the person.