How they're viewed has little to do with these decisions. Harding is seen as a weak President who was manipulated by those around him and who allowed corruption to flourish in his administration. The most famous example of this was The Teapot Dome Scandal. He may also, much like his successor Coolidge, have become associated with the boom that preceded the Great Depression.
Wilson is, unfairly I think, rewarded for leading America during WWI. This is in spite of the fact that he promised to keep America out of the war and managed to lose the peace that followed. Besides upholding sedition laws he did a number of other thoroughly un-liberal things.