Sean,
My experience says definitely 'yes', but not necessarily for the reasons you stated. It does depend upon how you plan to advance your flying training.
I did my PPL in 1982, then considered commercial flying in the late 80's at the time the BCPL came out. Doing the IMC rating I believe lifted the quality of my flying an enormous amount; I'd say it's like doing the PPL course 'properly', with much better discipline in the flying that, with further specific tuition, I was able to carry forward to successfully complete the CPL flying test. The IMC exams aren't a great help with the CPL/ATPL papers but they do help to keep you focussed on a little academic work.
In the event, I didn't get further than the BCPL, as I didn't qualify then for a Class 1 medical. Bizarrely, under JAA, I now do, but a little late for me now. I'd strongly advise anyone considering a professional aviation career to invest in the medical first, to save disappointment and money later. Someone I knew in the early 80's got a cadetship for ATC at Bournemouth and then failed the medical (eye problems again).
Although I've let the BCPL lapse I keep the PPL going, renewing my IMC rating for the umpteenth time last week - an SRA into a military field just for something different, a little stretching and great fun!
Personally, I've always regarded the IMC rating as a 'get you home service' rather than carte blanche to go plunging about in a light single in unsuitable weather. It taught me more about proper respect for the weather and I suppose it was frightening myself a bit on a couple of occasions that also pushed me towards it. I think I was a little lucky that my post-PPL over-confidence didn't get me into real trouble.
Anyhow, the best of luck with your chosen path.
Cheers,
The Odd One