In retrospect I know why: it has a self-enforcing feedback loop that leads to the rich getting richer, and the poor getting poorer. Thus the outcome of the game is often determined very early, but the game still drags on for long, being not much fun for most players.
The same feedback loop can be found in "The Settlers of Catan", though less (the poor don't get poorer, it's just that the rich grow ever faster). I liked it too, but it's not fun for too long.
An example where it's done differently is Dominion, where resources for development and resources for winning are distinct, but mixed into the same heap. During your turn you take a fixed number of cards from that heap, so if you have many winning resources, your progress actually slows down.
And of course there are also lots of games where the current position doesn't really affect your chances to progress. In the long run I like those (and the ones with negative feedback loops) better than the ones with positive feedback loops.