I very much agree with what Metoo said, below. Especially his description of exploring the world of diapers during puberty. That could have been ME talking!
But in addition to that, I should add that diapers appeal to me on so many different levels. There's the sexual fetish level (I love looking at my diapers and plastic pants, looking at me in them, touching them, feeling them against me, wetting / loading them, smelling them, etc).
Then there's the "escape from the rigors and responsibilities of the adult world" aspect. Adults have so many responsibilities and issues to deal with and sometimes it can be stressful. But wearing diapers is the perfect way to escape from this and abandon all responsibility--even the responsibility of getting up to go use the toilet. So in that regard it does remind me of my childhood where others took care of me, fed me, gave me a place to live, etc, and all I had to do was wake up every day and enjoy life.
I think many of us don't want to leave this time of joy and comfort by having to grow up--the "Peter Pan" syndrome--and the first thing your parents do to start you down the path to adulthood is tell you "OK it's time for you to be a big boy/girl now" and take away your diapers. I know that mine certainly did and I was so young that I don't even remember it. And I'm certain that this is much of why I was always fascinated with and envious of all the other kids and their younger siblings who were still in diapers when I was a kid, and why I developed such a love for and sexual attraction to them that I still have today.
So yes I do think that wearing diapers is a way to return to this joyful time in life. And I think the reason I love the humiliation aspect of it is, that's my way of expressing that I know this isn't "socially acceptable" but I love it and I'm going to do it anyway and I don't care what anybody thinks!
One more thing that I'll add--in a few weeks I'm going to have a few days all alone in the house, which will include lots of diaper fun. It will be one of those rare times when I can get them all out, stack them up on the dresser, put my diaper pail next to my bed and go around wearing diapers and baby clothes for a few days of fun and stress relief. And with this in mind, I just ordered a toy on Ebay--a Kenner building set from 1961--which was my favorite toy when I was three years old--and I'm looking forward to spending a few hours sitting here playing with it while wearing my diapers. Should be fun!