maybe part of the reason it's hard to get over the goofiness of banjos etc. is that (I'm assuming, but maybe just protecting my own lack of knowledge) you're not very familiar with the idioms that it's used in? ime it's more common for people to criticize music for being corny or sounding like cartoon music, etc. when we don't understand its idiom very well--cause you recognize the idiom-signifying features but not the expressive twists and nuances. like how rap is often seen as a ridiculous, unintentionally funny genre by people who don't listen to it; they only pick up on the tropes they recognize from snl parodies of it.