Yeah, it's always been kind of an odd topic.
Hugs and Tugs' personalities have been equivalent to young kids, if I had to guess I would say six years old. And yet they've always worn diapers. This is very different from the cubs in the 2nd movie that pretty clearly act like one year olds.
You could argue Hugs and Tugs seem slightly younger in their debut in The Freeze Machine, but even so, they still seem like kids.
I think this was more common in older cartoons, though. The idea of them wearing diapers makes them seem young and innocent and cute, and I actually agree it makes them cuter. In the more modern versions, the cub characters don't wear diapers, which makes more logical sense, but I find less cute.
However, The Turnabout is the only time that I can recall that it's actually mentioned that they need/use their diapers. In every other instance, it feels more like a symbol of their youth and innocence rather than having a practical use.
In The Turnabout, it does feel kind of odd to have a scene where they need their diapers changed. All of the other stuff they do is typical kid behavior. Even the crying is a little weird....it's forced. The only other time I remember Hugs and Tugs crying like that is in a joking way in The Music Video episode.
However, I guess it was a big opportunity to play into the trope of boys not knowing how to take care of babies and how to change diapers, which kids probably found kind of funny. Even in older cartoons, the idea of changing diaper being unpleasant is used. Also, it can be kind of funny seeing that Champ and Bright Heart know so little about it that they put Hugs and Tugs' diapers on in crazy ways...especially since Hugs and Tugs know how to put their own on in a flash.
Despite all of that, I like the idea that the icky part of it is so subtle..it's just hinted at. Instead there's more focus on the powder and clean parts...kind of like in I Care for You. I always like how old cartoons ignore icky stuff like that, not even saying the words. Very unlike modern cartoons that seem to point it out clearly.
Of course, I still like my theory that all Care Bears don't actually need or use diapers, and that the ignoring of the icky part lets you think that it's not even there. I like the idea that they just needed new clothes like any regular person does from sweating and whatnot.
Or, my other theory is that Care Bears poop sweet, clean smelling things like sprinkles or rainbows.