I wanted to share some thoughts on this topic. When I was handed my PPL, the DPE said to me the cliché line "It's a license to learn". When I got my instrument rating, my instructor said to me "you are now rated to scare yourself, just don't kill yourself!"
I have been instrument rated since the early 90s. The instrument rating for me was a lot more challenging than the private license but also much more rewarding. The challenge came from not only the physical act of flying with reference to instruments but also to understand the entire ecosystem as it relates to instrument flying. Whether it is knowledge of the regs, performance specifications of the plane, avionics, approach procedures or weather -- there is a lot to know and more importantly comprehend and be able to use when & if needed. Any knucklehead can break through a 1000' thick stratus layer and survive. But only a competent and current instrument rated pilot will have a chance to deal with all the factors that you will encounter during an instrument flight.
What troubles me is when I see an accident report of an experienced pilot. Especially this one: http://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20060501X00494&ntsbno=CHI06MA115&akey=1 The pilot involved in this accident was no novice: http://en.wikipedia.org/wiki/Albert_Scott_Crossfield
So if a pilot as experienced as Scott Crossfield can be involved in a weather related accident, what chance did these guys have?:
http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20101028X12506&key=1&queryId=be3443dc-5ff8-444a-8a64-6b4943c8185c&pgno=3&pgsize=100
http://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20080219X00205&key=1&queryId=be3443dc-5ff8-444a-8a64-6b4943c8185c&pgno=4&pgsize=100