I think those that think she shows zero personality haven't been keeping up to date with Britney lately, those days are long behind her, she was unhappy for a long time but now she is in a good place, her recent Vegas performances have been absolute fire, she has her passion her back, her new single has been planned properly, something her last album lacked, between 2013-2015 she got her magic and passion back.
She does NOT look dead behind the eyes, she gets nervous, and she's shy, so she appears meek, but on stage, she is a complete diva, that's how she expresses herself.
Anyone who thinks a 33 year old should be performing like a 19 year old isn't fair, she's had knee injuries, that's the main cause for her decrease in dancing, its not that she can't, its that she's very nervous to dance all out on a knee that could dislocate at any minute.