I became a stan after hearing Hold It Against Me and I ADORE Femme Fatale because after listening to that album I decided to give the rest of Britney's discography a try (Glad to see someone else experienced the same!!). Femme Fatale DID expose Britney to a lot of the younger generation and I even saw a few young kids at her concert when I went. I mean, yes, the sales weren't the best, but let's remember that Blackout was Britney's lowest selling record before Femme Fatale was released and Blackout is still one of her most flawless efforts to date. Sales don't justify the quality of an album.
We had a well-performing tour (Again, it had an average of about 900K per show which is quite respectable) and good videos and singles performance on the charts. I really don't think there was a MAJOR reason to abandon Britney during the FF era aside from maybe her performance skills. Because we did get some really cute interviews (the ones from the UK come to mind).
Just my thoughts.
