Outside of Crichton and Aeryn, the rest of the cast just had simplistic and uninteresting personalities. D'Argo is an angry brute with a soft cuddly heart, Dominar is a greedy pig, Bialar seems to fill Dukat's role in DS9 except he's much less interesting and I can't stand Jool's screeching and whining. Something goes wrong, everyone (including the entire audience) looks at Rigel. D'Argo just fights his way out of all situations. While funny, all these elements just made the show too predictable to keep my interest.
Overall, I guess you could say I did not like over half the cast and their constant bickering over the smallest of issues.
Sure, I can buy that you (and others) didn't care for some or most of the cast..... I've found that Farscape isn't for everyone. A good friend at work who really likes Sci-Fi watched the whole series not too long ago and I was surprised that he didn't take to it like he did other shows. He seems to enjoy the more straight-forward approaches to Sci-Fi like Stargate SG1 and ST:TNG. Nothing wrong with that......just a matter of taste preference really.
Anyway, I was just responding to the "childish" description you used which having read this really meant that you thought some of the characters were too 1 dimensional and predictable. I may not agree with your assessment, but at least now I understand it.