The old system was far better, and this one has cost people their jobs.
What old system? Can you elaborate on the exact job loss problem?
The UK has never provided a free web based flight plan filing service. The only service I know of has been
www.homebriefing.com (run by Vienna ATC) which charges Euro 37/year flat rate for the first 10 flight plans. HB does work and I've been using it for years, as have many others.
Why do they have to have your licence number?
My guess is that since this will enable people to file flight plans via a
direct internet gateway to the AFTN, and thus could be used to file bogus flight plans, they want to be sure that the login details go to a real pilot and not some hacker.
They don't actually need the CAA license # because you could for example be flying under a German PPL, or an FAA PPL/CPL etc. But they will want to verify your ID.
This is not the same thing as faxing a flight plan to Heathrow, where if some tw*t faxed a load of bogus ones then recipient will just bin them. I have heard a rumour that the services such as Heathrow may disappear in the future and we will all need to use online sites like this. Personally, I have never used anything but the internet - it is virtually mandatory already for notams so there is nothing new to learn.
The whole issue of online flight plan filing has been neck deep in politics for as long as anybody can remember. The speculation has always been that the powers to be dragged their heels because of the abuse fear. The UK notam site
www.ais.org.uk has been thought to always have been capable of the function but it was never implemented.
This dragging of heels is what enabled Homebriefing to start up and make money with a premium rate service - for doing nothing more than they were doing anyway, but they got some software which links their web interface to the flight plan entry desk and does the addressing via some sort of address database (which is tricky for VFR).