I think the only restomod I'd be tempted by is for a camping whip. Just to build something that's still retro (thus interesting) but had half a chance at being a somewhat reliable for longer rides. You don't really want to be dealing with old parts giving out on you in the rain, with bags full of camping gear in the middle of nowhere.
But I can see the appeal for others, as daily riders, Etc., for sure.
Just not for me.
In general I feel like anything that keeps an old bike on the road/trails is a good thing. So have at it!