I can see why this is such a controversial move but I think it's broadly positive and is another step forward in institutional recognition that the NCN (and UK cycling infrastructure generally) is largely unfit for purpose.
I can't think of a single NCN route I ever follow without carefully researched diversion. I suppose NCN 1 from Haymarket to the FRB? But even then I've started avoiding the increasingly obstructed and bizarre section after Dalmeny. (The latest hazard I spotted was an encroaching wire fence.) NCN1/775 to Perth is mostly nice, but I tear my hair out trying to find a route avoiding the awful infra in Dunfermline and I seem to recall that the bit at Bridge of Earn has claimed at least one life.
Surely, then, this a network significantly failing to meet its goals? I struggle to imagine the cyclist who could actually happily tour NCN routes on trust without fear or frustration. Someone riding a fairly chunky hybrid, equally comfortable on big busy roads as well as muddy unlit paths behind housing estates, but who also has the fitness and strength to lift their bike over unexpected hazards and steps where necessary. It's certainly a breed! Not a mainstream one though I don't think.
Fundamentally it feels like a lot of the problem - both generally and around this particular issue - is that sustrans is trying to fill many roles which should really be delivered by almost as many different individual bodies. Its roles often mutually hamper each other, and its structure makes it difficult to achieve success for many of them.
It has many roles which should be fulfilled by one or many well-funded fully (non-charitable) public bodies...
- Mandating national standards for cycle infrastructure
- Identifying investment opportunities for cycle route upgrades
- Identifying, maintaining and signing a "national standard" accessible route network
- Maintaining and signing substandard but otherwise useful cycle routes on roads and paths
- Identifying and investing in general streetscape improvements in cities and towns
...as well as some which should probably be owned by enthusiast clubs/charities which sometimes work with landowners and public bodies, or a National Park authority-style public body...
- Identifying, signing and grading mostly off-road routes
- Identifying and promoting longer routes for more experienced and hardy touring cyclists (eg. C2C, maybe Caledonia Way)
...and finally some which probably fit better inside pressure groups like Spokes or even Critical Mass, rather than a quasi-public body which has to be careful what it says...
- Vocally promoting large-scale investment in cycling at a national and local level
- Lobbying for major law changes to protect and promote cycling
- Lobbying for radical measures to generally reduce motor traffic
To take roads equivalents of these, you're essentially taking bits of the MoT and Highways England, combining it with some motor tourism publishers and topping it off with a sprinkle of that guy who's always quoted in news articles criticising speed cameras and parking charges. They don't do it that way for cars, so why should they for bikes?
When I look at it this way, it's easy to see why there's such debate. Everyone will have a different 'idea' of what Sustrans and NCN is meant to achieve based on a combination of the goals above and will either see this as a betrayal or a step forward. I'm pretty hopeful its the latter, but much bolder changes are needed to really unlock the benefits.