So long as GO remains at the hourly all-stops 2WAD threshold, with no added VIA service, they aren't impairing anything by staying dark. Travel times might be impaired by 30-60 seconds if signals further ahead are restrictive.
If more frequent service were desired, the signals would be needed as they would enable trains to follow each other more closely.. One of the three tracks from Wice to Malton has never had the signalling cut in, although all the components are in place. This track would be needed if there were more express trains needing to slide around the local GO trains.
If you are suggesting that it was prudent to rough them in early, my question would be, how many years ahead did the planners anticipate when they did the plan in 2010ish.
- Paul