@Zep Tepi is right about finding silver in the mountains. It's also possible that you have just been extremely unlucky.
As far as replayability, that depends on what you want in a game. I have been playing it almost since it came out and still am. I have played it through at least ten times. Each seed is different so you always have new territory to explore, The bosses could be easier or harder to find or get to. OTOH, there will be fewer surprises and you will have already solved the problems.
It sounds like you get the game and enjoy it. Look at it this way, although the game was a sensation when it was new and many people have since wandered off to other things, it still has a strong following. So there is a good chance that you will continue to enjoy playing. The only question is, are you the "been there, done that" type or one who says, "That was awesome! I want to do it again!"