[Comes out of closet]
I'm a ranger too.
My section is 90% on road, can be ridden on a road bike and goes somewhere vaguely "useful" (the centre of Peterborough).
That's not the point though. The routes are not for "fast utility cycling" - very few people willingly cycle 15-20 miles to go shopping. Their utility cycling will be from one village to the next, or from the outskirts to the centre of town, and for that they'll take whatever route goes straight there.
I cycle 15 miles to Peterborough daily and have met a fair few people who do the same journey. No-one takes the direct, smooth road route (13 miles), but neither does anyone use the NCN route, they take the compromise between quiet roads and directness.
IMO the route is wrong, because it neither takes the route everyone else chooses, nor does it take the most attractive route. It misses out a long section of quiet single track with stunning views, in order to include a section of cycle track. Unfortunately the cycle track in question runs down the side of a busy trunk road. I'm working on that point, but it does mean the cycle track gets maintained.
What I'm trying to say is NCN routes are generally useful for what they are trying to achieve, but they are slightly flawed (not flawed enough to warrant being "despised"). What they need is more people like Oscar's Dad and others on here taking on ranger duties rather than whinging about rangers not being proper cyclists.