The party isn't getting whiter. There are more important faces of color at this convention than ever before (ie not just tokens).
The country is getting less white though so the party that has always been the racist party in the modern era will lose some ground.
And the economy is deteriorated. And why should Romney be ahead after all the reasons you listed suggesting why he shouldn't?
Their elected body is not whiter but they are losing with minority voters. One could argue Obama being black is a big reason for it, and it could be true, but no one can argue the GOP is improving their standing with the hispanics and blacks.