Because they are much better at crony capitalist table-tilting than the Pubbies.
Sad but true. The Republicans have decided that the best way to win against Democrats is to adopt their strategy: supporting crony capitalism, pandering to racial minorities, etc. The trouble is, the Democrats are much better at these games than the Republicans are because they've been at them for much longer. Why vote for a cheap imitation of something when you can get the genuine article?