I realize this has been suggested before, but I would like to broach the subject once again.
Forge Multipart support.
With the current cabling system, putting machines of differing power tiers in close proximity is a bit ... clunky, to say the least. Particularly if one doesn't have the spare resources to spend on transformer upgrades, or simply doesn't want to, whatever. With FMP support, you could simply toss a 'cover' block up and stop cables from canoodling.
Additionally, it would be a very nice way to route things like wire from Project:Red. You could basically use the same pathways as the power cabling and make things look very nice indeed.
It would even allows us to hide power cabling in a 'wall'. (Yes, I realize that you can just spray construction foam on the cabling, but it's nice to be able to make the block truly look like almost anything.)