It would be nice to have a GUI for it, but it’s not that complicated. You have to set up a couple of things the first time (some of which are unavoidable, such as having to enable developer mode, OEM unlocking and USB debugging, and getting the unlock key from Sony), but installing it is as simple as entering the command to unlock the bootloader, and running flash.sh.
You could probably make a tool that downloads all of the required files and retrieves the unlock key from Sony for you, but you’ll always have to jump through a couple of initial hoops first.
Otherwise, what do you suggest?