I think because he has a very recognizable sound and a kind of identity. You know, much stars are going to, for example, the Jimmy Kimmel Live show whith much glitter and glamour and loudly taking about forever what unimportant things. But Mark doens't, he is serious and has a pure heart. He is the kind of artist that wants to play for 1000 people too instead of a World Tour in stadiums for at least 25.000.
And another thing: you pay what you get and you get what you pay. He is not coming hours late or so and he doens't kick out fans like Axl Rose is doing ('Bye bye Kumar!'). I was at his concert in Zwolle (Netherlands) and a fan walked close to the podium with a large DSLR. Artists like Rihanna or even Madonna would go immediately home, they have sercurity rows for those people who want to shoot a picture with a camera which is illegal bringing into concert. But Knopfler hasn't placed securtiy in their so you can almost tough him. And it's very normal to run before the encose to the podium at a Knopfler concert.
