IMHO a really great singer needs four things. These are: Technique - Ideas - Taste - Charisma
        
Technique alone – however excellent – is not sufficient. Without a modicum of taste, an idea or two and a dash of charisma, technical perfection quickly becomes boring.

Technically sound performers who are blessed with good taste but bereft of original thoughts may still build long-lasting careers - provided they (or their management) have the wit to borrow good ideas from more creative artists. But without charisma they will never become superstars.

Whereas once-great artists who retain their charisma can still pull in big audiences, long after they have run out of ideas, technique and taste. It's not fair, but that's show business, folks.

Wassail!