I just don't get how Britney doesn't even seem to want to sing live anymore when, watching all the old footage of her as a child and a teenager she seemed to absolutely LOVE singing live. You can see she had a real passion for it and really belted out songs with real power in her voice and wow, the way she held some of those long notes! For someone who seemed to love singing live in her youth it's strange that she has no desire to do it today. Damn, I'd feel so restricted just miming to songs the whole time. I'd be constantly wanting to just belt out the songs instead of silently mouthing the words, where is the satisfaction in that?!
I do think her smoking for so long has probably ruined her singing voice, like others have said. I know how smoking damages a voice because it damaged mine. I used to really enjoy singing and, whilst I was far from being great at it I used to have a fairly decent range and could hit the high notes. I smoked in my late teens but thankfully not for long. However, over the past decade I started smoking again (stress and things going on in my life made me start up again, stupidly) and I smoked for about 5 years before I finally gave up again. During this time though I noticed how much my singing voice change and how limited it became. I just could not (and still can't ) hit the high notes anymore. Even mid range is a struggle. My voice became deeper and croakier. I just can't sing anymore and I know smoking did this. What else could it be? It's not like I was a professional singer who'd been on the road touring and over-sang over the years to damage my voice! The change in my voice over the space of a couple of years (when I was smoking) was drastic. I'm forever kicking myself for taking up smoking for the second as I used to enjoy singing and just can't do it anymore and it really frustrates me. Even though I quit smoking years ago now my singing voice has never returned, it's permanently damaged. I wonder if today Britney regrets damaging her voice, either from smoking or from adopting the vocal style that was unnatural to her (or both). It's such a shame because she had a real vocal talent and it's sad to see her just mouthing the words to all her songs throughout entire concerts! You'd think she'd be embarrassed to be lipping to old CD recordings of herself year after year! I know it's hard to sing and dance at the same time but the fact she started miming even her ballads (during POM in Vegas, I mean) when standing still or sitting down somehow tells me that her voice really is limited now, and that's such a pity.
I too would love her to do a stripped back "unplugged" type of concert where she can just sit on a chair or stool and belt her out songs live, but maybe she is just vocally unable to do that anymore. A damn shame and I agree with others, a great waste of talent!