I assume you've seen Utena (given your fondness for PingDrum)? It's clear Enokido was going for the same formula as he used there; it's the "magical girl" episode trope, introduce a character with an emotional disturbance that only gets solved through beating the crap out of them, rinse, repeat etc.
The difference being, of course, that Utena's episodic characters are memorably tormented, while Star Driver's were flat and uninteresting (as you mention before), so the repeated structure is less obvious and irritating. The conclusions of the fights are no less obvious (Utena only clearly loses once in the whole series) but it doesn't matter because you don't care if she wins or not, you care about how the story resolves for the episode's main character.
Star Driver couldn't even manage a Saionji, let alone a Jury type, in its cast, so of course it seems pointless and repetitive.
Utena is also wrapped up in layers of visual invention that Star Driver didn't have despite its vastly more flashy animation.
Yes, Utena is a particular favorite of mine.
And while Enokido was using the same basic format, it also made it abundantly clear to me that Ikuhara should get most of the credit for how Utena turned out, because Enokido wasn't capable of making even a single character in Star Driver feel sympathetic.
I'd say there are a few other factors that contribute to why Star Driver's issues are a bigger factor than they were with Utena. While Utena pretty much never loses, it was always conceivable that she could lose. The format of Star Driver made it obvious that Takuto could never lose, while even if you didn't think that Utena would lose, either, the show could at least hold that possibility out there. Beyond that, the duels were really a much more minor aspect of the show, compared to the sometimes quite lengthy fight scenes of Star Driver.
And when you combine that with Star Driver's utter failure to make you care about any character, it makes the whole thing feel meaningless. Another big failure is the sheer size of the cast. Utena keeps a largely manageable main cast, with some other characters who come and go for a specific episode or two. Star Driver's cast is bloated to near Code Geass standards, with the characters all being just as replaceable. This is a cast size that could function for a year long show, or a long running series, but not for a two cour series. And the characters all just seem to sort of consistently tread the same ground. Star Driver takes it further than Utena in this regard in that not only is every episode the same, but every story arc is the exact same.
A show like Utena has a set format, but the episodes can still deviate greatly in terms of the emotional content, while Star Driver feels like every episode is actually the exact same, with the characters all going through the exact same motions.
When you bring up the visuals of Utena, the metaphors and symbolism and thematic resonance, then it's no longer even a fair contest. We're comparing a gourmet steak to a cow pie.
Forget Revolutionary Girl Utena. Star Driver fails in character development and variety of story arcs even compared to Bleach