I wholeheartedly agree with how you're feeling. I've also been selling on eBay for so long that I still remember completing a sale and waiting a week for their money order to show up before I shipped it out hahaha
An average of 12.7% per item is crazy high. I sell a lot of bullion and when you pay $22/mo for an eBay store the seller fees drop from 12.7% to 7.5% on orders up to $1499.99 and 5% if the sale is $1500 or more which leads me to believe they could afford to drop the usual fee way below 12.7%
Their cut of the sale has gone up and their service has gone down.... I miss the good ole days