A $15 better psu is a timing and speculative thing. The builder has only so much time to work with and has only newegg to rely on for source. There simply might not have been a better psu available. You are looking at retail sales prices today, not the day the decision was made and quite often you'll find only 1-2 units on sale at any given week and it's usually a $20-30 jump in prices between a quality 550w and a decent 500w. Now if you wanted a piece of junk 550w, that's easy enough for the same or less than the psu chosen. It wasn't a bad call, its a budget build, on a budgeted time scale in a specific source. I'd be quite happy with it as is.
It's a $20-30 jump in price to buy an aftermarket cooler.
Of course it's a nice build, and anyone who won a free system would have no basis to complain about it. But the decision to buy an aftermarket cooler and skimp on the PSU is questionable from a system-builder perspective. That is why we're all here, after all -- to discuss how build a rig.
I'm not saying, "LOL, dude who wrote this article is a moron!" I'm saying that if you're in the real world lookin to make a build like this, you should ditch the aftermarket cooler and pick up a higher quality PSU, even if it's at the same wattage. It's not a big deal in the grand scheme, but little decisions add up when you're on a tight budget.
Call me an old fart, but I suspect that a lot of the aftermarket cooler advocacy is just enthusiast reflex. If you're used to building overclocking rigs, you get in the habit of building around cooling, whereas the average dude building a low-to-mid-range stock rig really doesn't have to worry about cooling much if at all.
Likewise, an enthusiast -- someone who enjoys rebuilding/replacing his rig regularly -- probably won't place as high a premium on a rock-solid-reliable power supply.
And for what it's worth, I have a rig with an i3 3220 and a rig with an i5 4590, both running on the stock cooler, and both are cool and quiet. The i5 rig, which has a better case, is nearly silent. YMMV.