That depends on the definition of "up to standard".
Donkey Lane is a nice fast, dry scoot on a cyclocross bike in good weather, and I used to commute down it on 28mm Gatorskins too.
I'm against the tarmacing and sanitisation of the whole countryside, but some improved drainage would not go amiss.
"Up to standard" was intended to mean something that, like NEPN, you would actually get the general public using instead of sitting in their cars. Sealed surface with lighting (the solar lights from the canal would be fine for starters).
Of course it's true that people technically /can/ ride it (and we do, sometimes - in fact I often commute on it). But as people have commented above, this is not the countryside. It's brownfield / heavily developed residential terrain.
It's not as if there's such a shortage of outdoors in the Pentlands that we have to keep thoroughfares in Edinburgh unsealed to remind people what mud looks like.
And tough luck if you have a wheelchair :)