As for the AMD one I didn't think that one through properly, originally planned for a less intense CPU, didn't swap the mobo out accordingly. However, there aren't any suitable mATX mobos for the 8350 (or am3+ in general) if you want performance comparable to a haswell.
No, you don't "need" a super expensive motherboard, but my consideration was to keep the mobo for as long as possible. At least in countries where building your own computer is a hassle because of consumer laws, having a reliable mobo with a 5 year warranty helps if the motherboard dies sometime even after those 30 days. It would be more reliable to send it to asus than to let the store itself send it off to someone for a diagnose only get it back asking ~$500 to fix it.
Sure I could have gone for a cheaper mobo, but I was thinking of overclocking with watercooling at a later date. (Albeit with a different case, but again, didn't care to make a new build just to give an example)
You're right, there are no suitable m-ATX boards that will properly support the 8320/8350. If that is the form factor you're set on, you may want to just go with Haswell.
I went with a mini-ITX for my recent build and hence, to get the performance I wanted with a $1000 budget, I had no choice but to go Haswell. Not that I have a problem with that, it's ridiculously fast. No regrets. :)
I agree spending a little more on a good motherboard that has the features and upgrade-ability you want is wise, and $160 is not THAT expensive. I was just merely pointing out that you selected a very good board for your Haswell option and yet chose a cheaper low-end board for your AMD option. Just to be clear, I don't think that Asus is a bad choice at all. ;)
Hehe yeh, I WAS looking for a better motherboard for the AMD one now that I think of it, struck me as odd that none of them cost more than $70 tops. I really like AMD, so no, if I could have gotten a more expensive motherboard for it, I would. :P