Quite right. I do agree with everything you said and I second it.
But, hard-coding the UI design in cpp, instead of using a JSON definition brings us no closer to a platform-independent UI.
In my limited experience it is very hard to design platform/device/graphics-lib independent systems, unless development on those systems is progressing, to some extent, in parallel.
I do trust your judgment when you say it can be done afterward as you know far more than I regarding this specific system.
I do realize we cannot spread a small community like this one too thin, but, If 1-2 people interested in another platform, Android for example, start putting a couple of screens together, in parallel with the clutter effort, it would probably be easier to avoid unintentional lock-ins. (I mention Android as it seems to be raining Android tablets)
I hope this post is not too off-subject. I'd hate to interrupt the clutter discussion. I really feel that clutter is a good call !