First of all, thanx for the vote of confidence there, man!
What Mark said especially holds true - if Maiden or Metallica, etc. didn't have the management they had working so hard with them, they wouldn't have been anywhere near as successful as they were. You know me, I think Maiden are absolutely brilliant but if it wasn't for mr Smallwallet, they would have either taken 10 times as long to do stuff or be a very minor player today I reckon...
What Phloggy said was sort of true now too in a sense - there's a wide spectrum of bands and there's just so many of them to choose from now in heaps of different subgenres.
Remember back in the 80s when a new record came out? You'd play the thing to death 'cos it was like "wow - this is genius! And there's nothing else like it!" These days, for every good album, there's 10 like it released at the same time since it's become so cheap and easy to put an album out now! I know I could go out tomorrow (if I had more than 30c to spare! *sigh*) and buy 100 albums that have come out in the last 12 months and would probably never really even listen to them. Whereas way back when you bought something and then played it until you were sick of it and kept playing it until you loved it again!
Some of my fav' albums from back then really were pretty average releases now that I just became fond of because I played them so much! Onslaught is a great example - if some band released "The Force" now, they'd be bagged out something fierce and everyone would go buy one of the 20 other albums that sounded a bit like it that were done better. But since that album was the only one of its type, I listened to it and loved it!
These days, you're up against huge marketing budgets, a flooded market and a wide spectrum of readily available music from every subgenre. You need a combination of luck, great management, great record label and an album that's got enough cross-over appeal to hook in fans from outside the area that you specialise in, but also without *sounding* like you're doing that or you alienate the die-hard fans who only like your specific genre!
It's tough!!
As you've noticed by the post there, I don't have an answer! HAHA! That's just my thoughts!