Roddenberry wrote the lyrics so that he could get half the royalties from the sheet music sales. They were never intended for any other purpose.
To clarify, Roddenberry didn't just collect royalties from the sale of the theme music's sheet music -- he collected fifty percent of all
the royalties related to the Star Trek
theme music, including performance royalties.
Sure, I wasn't saying the sheet music was the only thing he got royalties for. But at the time, nobody had any idea how successful the show would be, how often it would get rerun in syndication or how many movies and sequel series it would spawn that would reuse the theme. In fact, the whole reason he horned in on the theme music, so the story goes, was as a hedge against the show's failure. He didn't expect to make any profit from the show itself (or at least was cautious enough to prepare for the possibility that he wouldn't), so he added lyrics to the theme so that he could at least make a few bucks from sheet music sales -- which, if the show had bombed, would've been his only real hope of seeing any profit from it.
Mister Atoz wrote:
Wouldn't that mean also that Roddenberry and Courage would get royalties ANYTIME the Star Trek theme was even QUOTED throughout the score music composed by the other composers??
Well, there's a credit for them on the CD box set notes whenever that theme is quoted, yes. Even on Courage episode scores, the cues that use the theme melody have an asterisk and a footnote crediting Courage and Roddenberry for the theme. And as a rule, being credited for something means getting a royalty/residual for it.