There's some VC money interest but I'd classify more than 9 / 10ths of it as good old fashioned wildcat open source interest. Because it's fascinating and amazing, because it helps us direct our attention & steer our works.
And also it's so much more approachable and interesting, now that it's all tmux terminal stuff. It's so much more direct & hackable than, say, wading into vscode extension building, deep in someone else's brambly thicket of APIs, and where the skeleton is already in place anyhow, where you are only grafting little panes onto the experience rather than recasting the experience. The devs suddenly don't need or care for or want that monolithic big UI, and have new soaring freedom to explore something much nearer to them, much more direct, and much more malleable: the terminal.
There's so many different forms of this happening all at once. Totally different topic, but still in the same broad area, submitted just now too: Horizon, an infinite canvas for trrminals/AI work. https://github.com/peters/horizon https://news.ycombinator.com/item?id=47416227