For me I love the wet feeling of the diaper and I masturbate in the wet diaper as well.
Wet diapers make great masturbation because I love the feeling of the wet diaper SAP rubbing against my penis and it gets me off really quick.
I wear disposable diapers all the time and use them all the time for both pee and poop and when I'm outside I'll wear the diaper until it's leaking and continue to wear it while it's leaking.
I will walk around outside in my fenced in backyard with just a diaper on without any pants and pee in the diaper even though it's leaking.
I love wearing wet and leaking diapers and hate to change out of the wet diaper.
The dry diaper is okay as well but I prefer wet and poop filled diapers because they get me sexually turned on and I love the squishy feeling of the diaper between my legs as well.
I haven't used a toilet in over 6 years now and as long as I can afford to wear diapers all the time I plan to wear adult diapers the rest of my life.
To me it just feels great and I'm not exactly sure why other than the wet diapers are good sexual play to me.