User adoption under 50%?

A few weeks ago, I wrote a blog post about user adoption and how critical it is to the success of your software. I just saw an insightful survey on CIOInsight.com that really drives this point home.

Interestingly enough, the participants agreed that user adoption would save money. They also stated that user adoption is the most important element in realizing value. However, over half of the companies surveyed achieved less than 50% adoption rate.

If user adoption is so important, why is it so rare?