Yes. Things like IntelliSense and code folding would be very useful. It seems though that the Hype API isn’t very large other than the few functions you have to use that are Hype specific like hypeDocument.getElementById() rather than document.getElementId().
I found myself using Brackets for this purpose. I am thinking of a Hype plugin for Brackets. A common practice is to use external editors anyhow.
I would really like to discuss alternatives here as well (something like companion apps of the sort you have created above). Such apps can even be built using node.js fairly easily.
I will be doing a bit of research on this myself and report my findings here. Any more solutions or alternatives are welcome.