The point is that you dont earn money from music sales any more. Its all about touring, touring, touring. In a time where everyone has itunes and can buy a song for 0,99€ or 1,29$ its worthless to sell million of records. Look at other top acts like Madonna, her last studio album Hard Candy (2008) was a flop just selling 3,8 million worldwide. But the tour to the album became the second highest-grossing tour ever with $408,000,000. So artists and record labels gaining their money from tours and thats why Ayu and Namie have much more concerts now than in the years before.
And when you look at the
List of highest-grossing concert tours you see that mostly all tours are from the 2000s.