Why?
It’s not considered a “staple on the Republican road to the presidential nomination”.
From another thread:
The Iowa/Ames Straw Poll was always just a party. They only started discouraging multiple votes and bused-in non-residents the last three cycles.
The 2007 was a political junkie’s fiasco, with most candidates skipping it and Ron Paul spinning conspiracy theories about Diebold voting machines.
The 2011 fleeced the candidates pretty good, but left a bad taste the Iowa Straw Poll is trying to overcome. Romney didn’t bother being there, and eventual second place national delegate finisher (and Iowa Caucus winner) Santorum came in a poor fourth.