There's no doubt that the IMC is an excellent rating, for all the reasons already given in this thread. The issue is not whether it's good to get the IMC, but how you act once you've got it. In my experience, the skills you learn for the IMC are much more 'degradable' (I can't think of a better word) than most of those for the initial PPL. Rusty skills with an IMC are far more dangerous, so the holder of the IMC must take the approach that it is not a blanket entitlement to fly in IMC.
I find I use the NAV skills whether in IMC or VMC, so those are pretty well-honed (always learning though). I make sure that I fly in basic IMC conditions often enough to keep competent at the scan and the workload. The one thing I haven't been able to keep up are instrument landings...so I just won't do one and avoid getting into the position of having to, until I get refresher training.
Get the IMC, but it's up to you to maintain competency, keep the skills fresh and be safe.