You've just identified two completely different reasons that people buy wheels:
Originally Posted by Wooden Tiger
(1) Reliability and strength
(2) Speed, meaning aerodynamics first and weight second
Now there's this magic triangle that says you can pick any two out of: strong, light, and cheap.
Before you go spending $500+ on a pair of wheels, you should put some thought into what you expect out of them, and then figure out whether you're actually going to get it.
It's sort of a "thing" around here that any "serious" cyclist buys a set of wheels, it's like some right of passage. Don't discount the placebo effect. Someone who spends a lot of money on something they think is better equipment is often motivated to push themselves a little harder, although it's possible to do that without spending money. Put a lot more faith into measurable gains.
A lot of racer people will tell you that as far as speed goes, a $500 wheel set isn't going to be an upgrade from a stock set, more like a sideways change.
But if your wheels are going out of true, reliability might be a pretty valid reason to consider a new pair of hoops. Keep in mind that good strong wheels are likely to be heavy. The tradeoff is that they're not likely to leave you stranded.
95% or more of the people in this forum buy wheels based on how they look and not how they perform.