The real question to ask is why the # of JAA PPL/IRs issued in the UK is around single digits annually - after adjusting for those in the commercial pipeline so looking at purely private pilots.
Of course the JAA PPL/IR (7 exams) is doable. The JAA CPL/IR (14 exams) is also perfectly doable. Everything is doable.
So why doesn't everybody who wants to fly in cloud just get on with it?
There isn't a single factor which makes or breaks the decision. It's a whole collection of things. The expression "death by a thousand cuts" is very appropriate here.
One factor, for example, is that most commercial students are young men with plenty of time on their hands, and little money. Whereas most private pilots doing the IR are older, often 50+ and with a pretty packed life. Slotting this thing into a young man's life is not the same as slotting it into the latter's life.
I know a bloke who has just spent 2 years doing the CPL/IR ground school ab initio. OK this is 14 exams whereas the PPL/IR is 7 but it took him 2 years. NO flying - just the revision and exams. He is far from stupid. He worked self employed on building sites for that time to make a living and that gave him the time for swatting. 2 years. How ridiculous, given most of the stuff is irrelevant to flying for real.
And I know one immensely bright (utterly brilliant I would say) chap who did the whole lot in a few months - but this one is in top 1% or less of the population. Not really a fair comparison.
One could sit here for an hour typing up yet another long essay on the differences and I am sure this has been done many times. After a while one loses the will to go over it yet again.
But anyway the JAA v. FAA numbers speak for themselves. These people cannot all be stupid, or the victims of misunderstanding (or worse, from schools trying to sell the ATPL syllabus only). They have weighed it up and taken the American route. They represent the vast majority of private pilots aspiring to instrument flight around Europe.
Ni Thomas - I agree 600ft is not right as a blanket figure. An ILS is a piece of cake to fly to 200ft unless one's currency is really horrid. But anyway there is no way to enforce a cloudbase (by which I mean prosecute if it is busted) which is no doubt why the IMCR has no legal limits other than the approach plate DH/MDH.