I would really like to see Spaces added if possible. This app is quite good and would be excellent to recommend seriously as a Discord alternative, with the mainline Element client being substantially slower and clunkier. Spaces support would deliver that.
I use them essentially like folders of chats, similar to discord having many rooms in one server, so I for example have a space for External Servers (I.e federated chats in other homeservers), a Personal space with chats only I can access, etc.
It's cutting edge, on the verge, or at the forefront of something.
X is used a lot in Prototyping and Experimental designations or higher end products (see Aerospace and chipset architecture). In a more "Layman's" Sense I would also assume that people associate it with being "Extreme/X-treme"
Have we lost the knowledge how to make native software? Do we really have to use bloated, memory hogging "web apps" disguised as executables? Is cross-platform really worth the performance impact?
Open source apps have a very limited amount of resources that would be better spent on bugs and features rather than maintaining a dozen native apps with feature parity