I haven't watched The Clone Wars more than once. I ultimately found it lame and very kiddy (yes I'm aware it's a kids' show before anyone says it), though I'm aware I'm probably in the minority as most people seem to rave about it.

Anyway, I don't think Cad Bane was at all threatening or a particularly memorable character. Boba Fett borrowed from the cowboy archetype, down to his gravelly voice, the stirrup sound effect when he walked, and his general demeanour. He was threatening and sinister from how he's presented - faceless, battlescarred armour, doesn't talk much.
With Cad Bane, you have an almost neon blue alien with red eyes, a cliche 'bad guy voice' and wearing a literal cowboy hat.
I don't understand why anyone finds these cartoon characters compelling. They're laughable caricatures; completely fine for the medium they're presented in, but have absolutely no place in a live action, more serious movie.

I understand you may not have meant to take absolutely everything about the character, but personally I see nothing about it that's of any use. He has the same lazy, derivative, and stereotypical character design as some of the CG Prequel villains, except it's even worse.