I agree Donny that every performer should put his or her own stamp on their tunes. It's not entertaining to watch a guy with his head buried in his sheet music. But I don’t think it's wrong to use a chart to learn a tune, or as a reference point. A chart is just like a road map. There are many routes you can take. It’s up to the performer. There’s plenty of room for creativity and interpretation.
I can see charts for a band or bigger to keep everyone in sync....but for a OMB player not so much more of a crutch and less audience eye contact. But that's just me.