Those (that I know) who went straight to helis were very well funded individuals, completely unlike the vast majority of the UK PPL customer profile, and while the scene does attract more posers than fixed wing (helis are a far more effective way to pull birds than fixed wing, so who can blame them) there are many punters who get into it because of the ease of parking and general versatility for ad hoc travel within the UK.
Very few people seem to get into f/w with any apparent utility objective, and indeed it is difficult to do so without becoming an owner or part-owner.
While these individuals do exist, a lot of helicopter pilots start because they love the machines, the hands-on aspect, the sheer versatility which f/w aircraft just don't have - in my albeit limited experience of f/w types.
I have zero personal operational experience of helis but having spoken to a number of the pilots (rare IR(H) types excepted) it appears that they do rely on the ability to easily land to avoid weather.
I'm not sure that this is true. We do talk as though it is! We do feel better knowing we can. But I've never actually done it, in 450+ rotary hours (not a lot really, before anyone tells me). And I don't know many people who have. And it needs to be done with a lot of care, or you end up flying at 200 ft below cloud in poor vis and becoming another statistic - since even helicopters can't make instant landings.
I have often toyed with the idea of doing a PPL(H) but it seems very hard work especially being nearly 50!
IO540, I don't give my age away on PPRuNe, but I wasn't very much younger than that when I started flying helicopters. You are nowhere near too old. That's a lousy excuse.
I strongly believe one should train, even ab-initio, in the same machine which one wishes to fly afterwards. Of course this makes instructors cringe.
No, I'm not cringing. I think learning on an R22 might make you a better pilot though.
IO540,
One thing you seem to have omitted in all of this is the pilot who flies for the fun of it. The pilot who doesn't necessarily want to go anywhere, and certainly not any great distance, but is happy doing a little jaunt on a sunny weekend. A f/w pilot like this quickly uses up all his/her local airfields and gets bored. The rotary equivalent can probably spend a summer or two at least landing in friends' gardens, local pubs and hotels, and similar places. And it probably won't cost much more, if any.
Finally, we're not all well-heeled. Some of us were well-heeled for long enough to qualify...but windfalls get used up.

One of my PPL students does manual work in Tesco. Another is a psychiatric nurse. Another is in IT, surprise surprise. The private owners tend to be medium-size business owners, but not the rest of us. We're just helicopter addicts.