Early cartoons were very musical, especially Looney Tunes which by contract had to animate to music owned by Warner Bros. Later, this obligation was removed, but Clampett liked music so much he preserved the tradition more than the other directors.
Many 40s cartoons used background music as sound effects, rather than actually animating to hummable tunes. (Scott Bradley's MGM music is the ultimate example of music not being used as music; instead it just reduntantly echoes the actions in the animation. Try to hum it!) Clampett usually only used sound effects music to link 2 different tunes together.
One of the things Clampett used tunes for was just to put the audience in a good mood and prepare them for the cartoon. Here is a great example of Clampett using really happy, bouncy music for no other reason than to give you pure cartoon fun. What a swell guy! He really loved his audience and always tried to please.
The animation is really happy and totally uses the music to show off what cartoons can do that live action can't. No one at Warner Bros. was more comfortable than Clampett at animating to music. When I watch Friz' few musicals, it looks to me like he is struggling to find actions to fit into the songs. It's very uncomfortable. There will be tons of scenes that aren't very entertaining that are just there to fill in the music. Very awkward-to me, anyway.
Clampett preserved the Fleischer tradition and added his own brand of wackiness to it. The Fleischers did the best musical cartoons ever.
Notice how all this cuteness and young hearted playfullness ends with a sick joke! Good old Bob!