My feelings exactly, ebay does not understand “unintended consequences” when ever it fiddles with something that works well, only to go wrong and affect something else as well.
Using ordinary mail is simple enough, why try to make it sound as though it is complicated, I think it is all down to fees and post and packing.
Packing costs for those who use “Simple” have to be in the price, so ebay makes a few pennies more in buying fees, and those pennies add up to a lot of money.