Ubuntu 官方的說明在「Bionic Beaver 18.04 LTS to use Xorg by default」這邊，文章裡面給了三個理由：
- Screen sharing in software like WebRTC services, Google Hangouts, Skype, etc works well under Xorg.
- Remote Desktop control for example RDP & VNC works well under Xorg.
- Recoverability from Shell crashes is less dramatic under Xorg.
講白了就是還有一堆東西有問題，看起來在 17.10 導入 Wayland 後沒搞定：
17.10, released in October 2017, ships with the Wayland based graphics server as the default and the Xorg based equivalent is available as an option from the login screen.
在 18.04 預設會用 Xorg，但系統內還是會有 Wayland 讓使用者可以選：
The Wayland session will still be available, pre-installed, for people to use, but for our ‘out of the box’ users the Ubuntu experience needs to be stable and provide the features they have come to expect and use in daily life and Xorg is the best choice here, at least for 18.04 LTS, but for 18.10 we will re-evaluate Wayland as the default.