DevOps (a clipped compound of development and operations) is a culture, movement or practice that emphasizes the collaboration and communication of both software developers and other information-technology (IT) professionals while automating the process of software delivery and infrastructure changes.-Wikipedia
Amazon EC2 Linux instances do not come with a GUI. By default, you need terminal access for all application configuration. Most of the developers/sysadmins working with Linux would prefer the command line over Graphical User Interface. But developers who are new to Linux would require a GUI for installing and managing the applications. Once you installed the GUI essentials on your server, you can access it via windows remote desktop client. If you are using Linux, then you can use VNC viewer as a remote desktop client. In order to have a GUI, a lightweight LXDE desktop has to be installed on your server.