When I bought the 50L, I too had a feeling of being ripped-off. The wide open performance is not acceptable, especially when you compare to the sharpness of 35L wide open. But seriously, you don't buy this lens to shoot at MFD and test charts/subjects. Go out there, take portraitures, candids. This lens is perfect. The slight softness actually brings flattering results to people's faces. I never thought of the shortcomings of this lens further.
If you want sharpness wide open, go for 35L or Sigma 85.