Before calling the Robin a groundhog, please be sure you are comparing like with like.
Thus, if you put 4 people into the lowest powered models you've got to compare that with a 152...4 up!
The lower powered models were only meant as trainers, 2+2 at a push.
Now start comparing the performance of the 160 and 180hp models with a 172, 182, PA-28 even an Arrow and then you'll see the Robin wins!
Best of the bunch must surely be the Jodel d140c Mousquetaire. Payload almost equals empty weight!!!