I believe another issue with the parallel taxiway was that it didn’t get planning permission to help quell the green lobby.
With a major A road and a river to bridge, as well as a lot of uneven land, it would be a huge cost for what could be very little use. The taxi times to 05R would likely be on par with the polderbaan in AMS, which seems excessive for an airport not yet at Runway capacity nor has extended periods of 05 use.