I have no insight to be able to speculate, so it's blind guesswork on my part.

Starriors was a spinoff of Zoids. Zoids started in 1982 in Japan and then migrated to the US and UK. It never got any animation until 1999 and then only in Japan. If I had to guess why, it might be because the Zoids were described as motorized model kits, not action figures, so they were probably marketed to an older audience and maybe advertised differently?

Zoids did get a Marvel UK exclusive comic in 1984 written at least in part by Grant Morrison.

Starriors came out in 1984 and was some kind of collaboration between Tomy and Marvel. Marvel did the mini-comics that were packed in with the toys, and did a 4-issue Marvel comic proper.

Masters of the Universe and G.I. Joe had both started their cartoons in 1983, it was a fairly new strategy to market toys. The Wiki says Tomy announced a Starriors cartoon but maybe they just couldn't get it figured out. Sunbow, Filmation, they were just figuring out how to produce these shows. Maybe Tomy tried to work it out with an animation company but it fell apart before they could get it done. Maybe the problem was they didn't have the cartoon ready when the toys were out. The toys hit in 1984 and they only produced 2 waves before the line was cancelled. It said the cartoon was set to release in 1985 but maybe it was just too late by then to throw more money at it.