No commercial airport wants a "spare" runway unless they REALLY need one. GLA, BHX and LHR have all closed runways deemed to be unnecessary. The cross runway at EDI is space for much needed parking, be honest. Using it requires a faff of coordination with Scottish Control so might as well taxi 90 seconds longer, use the main and allow some much needed stand building.
The runway in question was the hated original which wasn't aligned into the prevailing wind and saw EDI lose days of traffic at a time due to winter crosswinds, something PIK with the same runway alignment still suffers.