Reconsidering the altered ending

Yes, it's hastily written exposition. However,why does a charming, handsome and lazy man also have to be a heartless murderer? If Hitchcock had just embraced the forced altered ending, he could have made a remarkable ending better addressing both Lina's and Johnny's distrust and sense of helpless hopelessness. Instead, I think he pouted and threw in a shoddy contemptuous ending so everyone would know it wasn't intended.