No artist is truly original or unique. Just as no person is truly unique or original. We all take inspiration and ideas from everything we see and sense around us. Yes certain aspects of Any artists career is defined by what they listened to growing up and what they watched. Madonna broke many boundaries musically and visually for a female artist which has led to her having longevity and been inspirational for many younger artists.
Since many of the taboos and boundaries are no longer and we now live in a society were Internet and instant fame through mass media are accessible to everyone there are very little boundaries to break for new younger artists. This appears to cause the mass hysteria that troll bloggers and fanatic fans can't cope with. Especially the Bieber, Gaga and One Direction. This obsession with originality and who's copying who. Madonna has never claimed she has not been influenced or used others material in mixes and mash ups or that she has taken inspiration from designers or other stars. Just as Lady Gaga would never claim she hasn't copied or took inspiration from Madonna. The only people who make these ludicrous claims are obsessive fans that since Internet now gives them a ridiculous voice. The only difference us 15 years ago no one could get mass publication without it being checked for validity and fact. Now we live in a society that everyone's a music critic, style guru and appears to be obsessed with someone either in a admiring or hating way.
At the end of the day you either like or dislike an artists music if that person inspires you or makes you feel good does it really matter what anyone else likes. Lets be honest Madonna is going to continue making music her fans myself included will continue to buy it. She's generated enough income to be very wealthy for the rest of her life without having to sell another track.
What people don't like they make up just as the media does nowadays.