When Jolla first started mentioning the Sailfish X stuff, it did sound like longer-term, they were aiming to get a user-friendly cross-platform installer out. As far as I've understood, the initial release is more like an open beta (no Bluetooth, remember), and really just for the hardcore fans who want to support the project and get Sailfish on a solid device. The Sailfish X infodump didn't mention any ongoing plans for the Sony devices, so they may or may not still be working on a nicer installer.

If you mean using a shell script on a Linux device to flash a phone, yeah, that's probably a bit far for most end-users. If you mean running a tool that happens to flash a phone, well, firstly loads of people do that in the Android world anyway, and secondly how else are you going to get another OS on it?