I've been using the ais.org.uk narrow route briefing (NRB) for about 3 years now. During that time I have read so much stuff on these pilot forums about people having to wade through "too much stuff" but never understood what the problem is.
I think there is a massive lack of understanding in this area. PPL training doesn't help - I bet few schools teach ais.org.uk and much fewer will tell you about the NRB.
For starters, the NRB doesn't pull out too much stuff. If you plot a flight from the UK to say Greece, you will get perhaps 5 pages but a quick scan shows that nearly all of it is cr*p, for example notams from Greece saying they control their airspace and not Turkey, closely followed by notams from Turkey saying they control their airspace and not Greece. Then you might get a load of reports of unlit obstacles along the length of Italy. So what? It takes 1 minute to spot the rubbish. On flights within the UK (perhaps 99% of a UK PPL's activity) there is far less rubbish.
Next, ignore the stuff which was put in there to cover somebody's ar*e. Most notams are there just for that reason. Nav warnings (NAVW) are in that category. A NAVW might tell you about some military activity in an area specified by a horrid coordinate list. Do you have to plot it? NO, the military fly potentially everywhere anyway, ducking microlights and all the other low level PPL traffic. This stuff is irrelevant. The sky is big! If you fly at 600ft you are more likely to hit some parachute with a lawn mower on the back of it than a Harrier.
What matters is temporary restricted areas, temporary Class A, inop VORs, inop instrument approaches, closed runways, and stuff like that. In 3 years and some 500 hours and trips up to 800nm per leg, I have never had a notam list that took longer than a few minutes to look at, and that includes the bizzare Greek/Turkish stuff.
I also don't remember the last time I had to plot coordinates. Maybe once or twice. That's why I never bothered with a graphical plotting program. It would hardly ever get used.
The NRB seems to be a well kept secret!
There is zero prospect of anything changing. GA doesn't even feature on the aviation horizon, and IFR traffic tends to ignore en route notams anyway - it flies under radar control. The system is international and there are countless people around the world stuffing reports into the system about duff bulbs in lamp-posts.