Maybe...I don't say it to be mean, but we don't engineer much that works well like this. Seriously, you want warm blood, so heating (or insulating) your core goes a LONG way to being warm. If you have cold hands, you want them insulated from the cold/wind (hippo hands, wind block, etc., for instance) to reduce heat loss, and to directly heat them. Heated grips are mostly heating the bars, not your hands.
I hear you on the wires. When riding back in New England, I used to run heated vest/gloves. They were a PITA, but let us comfortably ride down to 18F. Below that, they just couldn't keep up. With the right unheated gear, staying warn into the 40s would seem pretty easy. We'll full vented gear down into the mid 50s at the track without much of an issue with just a base layer underneath.
Unless it is really cold, heated grips/seats seem much more like gadgets to me.