I think it's quite obvious why. Blaze Bayley was never popular to begin with. But with Silicon Messiah, he had a type of momentum (although whoever came up with the idea to release it at the same time as Brave New World? So utterly stupid), and a label that actively backed him, when there still was a respectful amount of money in smaller Metal acts. But while BLAZE made strong albums, he was overshadowed by Maiden and people quickly forgot about him. And in time with declining labels he had no financial muscle to make a name for himself other than "that guy who replaced Bruce Dickinson, but made crappy albums with Maiden and finally went away when Bruce and Adrian returned".
So by the time of Promise and Terror, he played some of his gigs (dunno how many) in bars where 50 people showed up, where yours truly had one of his best concert experiences ever. Shortly after that he had to let the band go because he couldn't afford to keep paying them.
And of course, Blaze kept on going doing what he loves, because let's face it, after his stint with Maiden you don't just go to become a cell phone salesman, especially since Blaze wanted the life of a rock musicians since he worked in that hotel reception a long time ago, when he started to sing. So Blaze kept on going and eventually released King of Metal, a bland album with bland songs and crappy, production. Which is why yours truly never bought the album.
Blaze is though, taking care of whatever fans he's got left. He's putting 100% into his performances, always signs autographs and chats with the fans. And because the fans he's got left still likes him they still buy the stuff he puts out. Like the Live in Prague DVD. I preorded it, and Blaze used that money to pay for the making of said DVD.
So, what I'm saying here is: Support the artists you like and especially so if they aren't very successful, because your support is the difference between a quality product put forth by the artist and a mediocre one.