@kaputnik: "Can they not already do that anyway by taking the Seafield Moor Road (with the horrible turn at the junction)?"
Yes they can, but that junction is really not at all safe. You are trying to turn right to join traffic that's approaching around a blind bend more or less behind you to your left - which is just about the worst place to see traffic approach from in a right-hand drive car (and must be just about impossible in a van unless you have a passenger to act as lookout). At the same time you have to check for traffic approaching from your right - more like straight ahead, in fact - in the lane you have to cross. This on a fairly busy road with a 40mph limit which is not always complied with particularly well, and with a secondary junction within a few tens of yards downstream.
If something like that was built today as part of new cycling infrastructure we would be wailing from the rooftops about it.
As the other non-bypass way to get between the two roads is a rat run that will, as Lezzles has pointed out, very likely have a new school built along its route, I can't bring myself to condemn a scheme that will send motorised traffic a more sensible way - especially if it means that, for example, Seafield Moor Road could then be prioritised to receive some high-quality cycling infrastructure.
But I would agree with Arellcat that the whole area is crying out for some quality cycling infrastructure, not least because of the quantities of housing that are slated to be built there.
I can't help noticing that the A701 relief road as now proposed will bypass the existing Straiton park-and-ride. The proposal seems to be crying out for a (long overdue) park-and-ride on the A702 south of Hillend, which would be accessible from the A701 as well via the spur road.