I think they did that when the new interface started. Unfortunately I don't know of any way to trick Safari back into the desktop view. Though they still offer that options for the Calendar.
You can get around it by using Atomic browser and setting it to identify itself as a desktop browser. If the standard view gives you trouble you can switch back to the basic HTML view at the bottom of the page.
Personally, unless I need to set up new mail boxes, delete tons of email {like I get that many} or something like that I'm happy just using the Mail app.