His voice was different, but his vocals still turned out very well.
Morrison actually had a good singing voice.
Perhaps his more “mature” voice on LA Woman suited the songs on that album. It does work on “Riders” especially.
Morrison’s voice improved as his time with the band progressed. When he first started singing with the Doors, one of the band members admitted his voice wasn’t very good. Which just proves a singing voice is like a musical instrument...the more you practice with it, the better you get.