If Nannes was so good why was he still playing for Holland in 2009?? He played his first 1st class game when he was 30. It's nothing to do with him deciding to prioritise T20.
Edit - should have read on!
"In February 2010 Dirk Nannes retired from first class cricket. He said, "Having been able to play just one game in the longer format this season due to injury, this decision will allow me to concentrate on 50 over and Twenty20 cricket and extend my career with Victoria and Australia".[4] The news was generally well received by fans as Dirk had battled through many injuries in his short career."
So he's quit 1st class cricket because of injuries.
another who misses the point
The point is without 20/20 cricket players would push their bodies more to play test cricket. Now they dont have to