Hi folks, I've already filed a request to be able to edit nodes of multiple objects. The reasoning behind this is that I constantly change shape of a drawing and that mostly consist of multiple overlaid objects so all of those need to be changed (currently one by one). I do, however like the way Inkscape restricts node selection within an object too.
So I think the following behaviour would work best -- you could only select from the shown nodes as it is now. But apart from working on a single object, Inkscape would also allow to select multiple objects first, then change to node editing and have nodes from all selected objects selectable.
Does that make sense? If we had a nice floating dock of the object tree, an object locking mechanism may be just as effective (lock uninteresting objects first, node select working on all objects). But we don't ;)