I think where it becomes really useful to have a screen is when a device’s firmware makes it possible to switch presets/patches from the hardware itself (as is possible with Axoloti).
It’s really cool to be able to switch patches/presets etc., and see what you’re doing, without having to connect a computer.
It’s also really nice to have some kind of visual cue about what the various controls do, for a particular preset/patch, and their current values.
That’s much less of an issue with something like Crow, of course, as you can’t change scripts on the fly without connecting a computer, and there’s basically no UI.