Looking back at when I first starting playing Dominion (back when Chapel was only for Witch games to trash curses), Moneylender's name can be a little deceiving. In life, borrowing money is bad. There's a negative connotation there. Like the event Borrow: you get an extra $1, but there's a cost there, you get 1 less card. So Moneylender, I'm getting $3, but what is it costing me? I lose a copper. Now I need to think about this: Is it worth losing this copper? I can't get it back. Well, unless I buy another. Maybe I should get a Market, so that I can play Market, play Moneylender, and then buy something + buy another copper to replace the one I lost. These are things I would think about.
Then all of a sudden you realize that you're getting $3, and that crummy copper is out of your deck. What other cards does this apply to? Maybe I need to go and take a look at that crappy $2 curse-trasher...