John D. Cook gave a great talk about 'Why and how people use R'. The talk resonated with me and highlighted why R is such a great tool for end user computing. A topic which has become increasingly important in the European insurance industry.
John's main point on why people use R is that R gets the job done and I think he is spot on. Of course that's the trouble with R sometimes as well, or to quote Bo again:
"The best thing about R is that it was developed by statisticians.Read more »
"The worst thing about R is that it was developed by statisticians."
Bo Cowgill, Google