As far as Barney is concerned, I'll admit that I would watch the show in its first few seasons, if only because I watched a lot of PBS as a kid. Was it a great show? No, but it was tolerable. Then long about 1998, it seemed like Barney suddenly went through something of an ATC era of its own, in that they suddenly changed/updated the theme song, replaced all the original kids with new ones, revamped the school set, added a bunch of annoying new puppet characters, and that's when I tuned out.
As far as adding music and sound effects to older inserts, that bothers me as well, the worst example I can think of being Ernie and Bert visiting the pyramid - the music absolutely kills it! The only exception I can think of to this practice was Mysterious Theater in which Sherlock Hemlock was searching for a circle - in that one, they actually managed to use the added music cues to great effect.