Dragon has a 1/350 Pennsylvania in 1944 fit announced as an upcoming kit
http://www.cybermodeler.com/special/2010_naval_manuf.shtml
As far as why Arizona? Well she is a sentimental rally point of Pearl Harbor. But if one looked from a contribution importance in war standpoint, I think any one of the sunk and salvaged to fight again battleships made more. Nevada, California, Maryland, West Virginia, and Tennessee, are all long overdue in styrene mainstream kits as well.
So your question is really just a matter of waiting for a release date.