One thing no one has mentioned is confidence. Personally, I have more confidence with a bait that cost 20 bucks as opposed to a 5 dollar lure. There may not be a valid reason for the increased confidence, but it's confidence nonetheless. On tough days I'll tie on the expensive boys and really believe that I have a better shot at some decent fish. I believe this to be true, but I can't say, and I don't think anyone can say, that it actually is true. What is definitely true is that you will catch more and bigger fish if you're confident than if you are not confident, and if you are more confident with a certain lure, then you will tend to catch more and bigger fish with that lure. So more expensive, higher quality lures may, if not directly, at least indirectly catch you better fish.
If fishing more expensive lures doesn't make you more confident, then you may not catch more fish with them. However, I do believe that the higher end lures actually do perform better on average, especially on difficult days (which, come to think of it, is probably why these lures give me confidence...). Plus, I hate tuning lures on the water, so this is yet another advantage.
Did I say before I'm not a bait snob?
Edit: I'm not a full-fledged bait snob yet, but will probably get to that point soon, especially with the huge rack of LC's at the new Cabela's 15 mins from my house.