Hi Dick
I don't think that it's a case of them having specifically decided that it's "safe". I think its just the way that the situation has grown up.
They've decided that you can fly IMC outside of controlled airspace and that since there is no requirement to communicate when flying outside controlled airspace then, ergo, you can fly IMC without reporting. They're not advocating it, but you're allowed to do it.
Bear in mind that most of this legislation was originally drawn up just after WW2!
I'm not aware of any mid-airs in IMC outside controlled airspace but there must have been close calls.
I will always avail myself of the best ATC service available (Why would you not?) - I'm very uncomfortable without a radar service and do everything i can to avoid operating IMC without one (Climb, change route, ask to enter controlled airspace, regain VMC). Generally in the southern half of the UK, above MSA, you've got a pretty good chance of getting a radar service (depending on the time of day).
OH