I hate to stir up the argument about illegal IMC flying, but I think there's plenty of evidence that it happens. I know of quite a few people without IMCR happily flying VFR on top (and flying IMC to get there). I watched dozens of them doing it on departure from the PFA Rally a few years ago. (It's possible but very unlikely that all those departing pilots had IMCR; the weather was much worse than forecast, but they were going to get home come what may.) PPRUNE and other bulletin boards contain various hints of people flying VFR on top with no legal way up or down.
Clearly one should be careful of the "it's going to happen so let's make it legal" argument, but I think it's valid if you can make it safe as well as legal by providing the training that leads to a qualification such as IMCR. Which is exactly what we've (currently) got.