As you saw in Superboy's coloring page, the Total Justice line was planning to include Wonder Woman.
When Diana finally did get a toy in Series 4 of the follow-up JLA line, it was a fully new sculpt, definitely not one that had been waiting since the Kenner days - she lacked the stylization of Total Justice, and was noticeably taller than the other characters. If you look at her art in the coloring book, it feels like her approved design was still being worked on: most of the drawings give her wild hair and the full set of armor, but the ones that have smoother hair are also lacking the little wings on her shins or the additional bracelets.
It's barely remembered today, but back then the Wonder Woman license was separate from the rest of DC, kind of how Spider-Man's movies are separate from Marvel's currently: Kenner had the DC license, but Mattel had Wonder Woman; Kenner would have known when Mattel's license expired, though, and likely assumed DC would be looking to get all the properties back together again, so it makes sense they'd have been working on a Wonder Woman they could release as soon as possible when that happened; but also, not needing to go into production right away, it also makes sense that finalizing her design sheets would be a slightly lower priority.
