Eshop isn't like other stores, most of the screen is loaded like a web page every time you change it. It means a lot of redundant loading and waiting on the Switch's crappy wifi chip to do more. I think the OS is more waiting to redo everything over and over than struggling. They could change this system any time they wanted on Switch 1 but if they don't at Switch 2 launch it's a bad sign they will ever bother.
I don't think they want to pull another Wii U, a poorly received successor of a extremely successful hardware. So they are being extremely cautious how to manage the marketing of their next console.