They have the .deb at the top of their download page, no need to install the PPA repository if you don’t want. You can’t get any more than “just downloading and double clicking an exe deb” than that on Ubuntu.
I will admit though, I wish there were an easier way to install PPAs.
You realize your computer won’t work without scripts, don’t you? And if you want your computer to do something it doesn’t do on its own, a simple script will make it do what you want. If that is your definition of sucking, then you need to go back to Windows, which is also loaded with scripts, by the way, so that sucks too.
I think AppImages suck as well, but this is not a reason for my dislike. A simple script that you can run on startup will fix that problem.
It can be much easier to install a PPA than using the command line to do so. I think it’s high time it was as easy as clicking on a (verified) “install this repo” type button on a page, and confirming, entering your sudo password from the launchpad website. I’d even be OK with building it into Discover.