I'm sure there is a place and maybe now is the time for what Nick advocates over in the USA.
But perhaps here in the UK we might see the whole picture differently:
Commercial helicopter accidents in the UK are few and far between - yes of course they happen and they are hyped up by the media (as do all high profile accidents) but in the whole scheme of accidents - they are few and far between (thankfully). This could be down to the professional attitude of the pilot and his/her training and of course what Nick is suggesting - the airways infrastructure designed to accomodate these highly commercial activities.
BUT, a huge swathe of helicopter activities live outwith this strictly regulated. highly trained environment and for want of a better description - this GA traffic causes the most amount of accidents.
One can't regulate this fraternity the way Nick suggests because as Crab stated earlier, the whole of our Class D airspace would need to be controlled and bang goes our GA traffic.
Helicopter flying outside heavy commercial flying is much more hands on, suck it and see, give it a go, PPL stuff (please don't think I am condescending here) - it's is the nature of the beast. Helicopters land in back gardens, land on main roads(HEMS) fly ultra low level, hover over water, tow boats - none of which is practiced by the FW fraternity in their GA world.
Helicopter flying is a freer form of aviation (whilst still adhering to the rules, I might add) because of the nature of the beast!
We/they don't want burdensome overkill of routes/airways/approach aids to enjoy their GA existence.
Yes - unfortunately it comes at a slightly higher accident cost than say heavily regulated commercial activity - but hey that's life isn't it?
In fact - is our accident rate in the rotary world - a cause for growing concern, in the UK, I might ask?
My computer therefore says - no. Sorry. The UK has enough regulation and infrastructure.
[I thought during your preamble - you were going to say that the problem was actually the pilot in all of this, but you went onto describe catering for accidents by leveraging procedures, aids, approaches etc; etc. The problem with accidents actually Nick IS THE PILOT, not the tree / pond / mongolia! Accidents don't care about the colour of your box (inside or outside).