Also we all know that with a cheaper processor you can get cheaper components as well. Saving $50 on the cpu, you can save $30 on the psu, $10 on the RAM, quite a bit on not needing an aftermarket cooler, a cheaper mobo that doesn't support overclocking or higher clocked ram. In the end you sacrifice some performance, but the cpu is the only thing you'll really notice. Yeah you could do the same thing for a pentium, but with an i3 I would want to spend a little more. If you need anything less than an i5 though, you really won't notice that big a difference between all the low-end processors. If you want a celeron for rendering for work or something, you're obviously looking in the wrong places.
The thing about these enthusiast forums is that everyone is concerned with benchmarks and not what most people spend their time doing. For the casual user, it doesn't matter if rendering a couple of videos a week takes five more minutes than a processor that costs twice as much. They both do the same thing pretty effectively.