Hmm sounds like someone at Filmation was kind of a weasle. But as I remember it, the actor who played Captian Marvel didn't matter that much. You just needed a big clean cut guy who fit the suit to hurl styrofoam boulders around. The tv show was cheesy good but I would have watched it alot more if Wonder Woman, specifically Lynda Carter, WAS in it.
From some of what I've been reading, though opinions may vary, Jackson Bostwick was the main draw of the show. He was the one who suggested doing the moral tag on the end of the show, and though they did not originally use it, they began to add the tag after so many requests for more of Captain Marvel.
I remember when I watched it, it was just such a drastic change when they replaced him; though I think Davey was adequate for the part and his softer spoken presence made him personable in a different way, he just did not have that commanding presence that Bostwick had.
Of course, from the Wonder Woman perspective, Isis ruled! Joanna Cameron was so hot.