I can see it working if one wants to customize the compilation flags of a few packages they have strong opinions on, but otherwise don't care about the rest of the system. Sort of like the binary cache in NixOS, where by default you use the binary cache, but you can customize parts of your system triggering a source-based installation for that parts.
I'm an Emacs graybeard, so complex keybindings don't scare me. My problem with ncmpcpp is twofold:
It relies on MPD which is always a PITA to properly configure. Pulseaudio always managed to make it not work on a fresh system. Hopefully with Pipewire it'll be better.
The config format make no sense whatsoever. Especially the one with keybindings. It's so cryptic I just stopped trying to understand it. Again, I'm an Emacs graybeard, to stress it as a point of reference.
The IMAP support has been more or less broken since the very beginning. Their custom labels make folders behave in a non-standard way and the IMAP itself is terribly slow compared to every single other provider I've used. I used to have dedicated workarounds in my email automation scripts for their weird folder semantics, for even such trivial tasks as actually deleting an email as opposed to merely removing a label from it.