Should non-responsive "friends" be unfriended?

Yes, give em the boot. What use is a "friend" who won't communicate with you?

Yes, but only after you've given them some time. Give them a month or so to answer back when you ask "Hey! I missed you! how's it going out there?". If they ignore you, discretely remove them.

Are you kidding? No way! I collect friends on facebook and deleting people would make my enormous friend count go down!

No, facebook "friends" who don't respond back are clearly too important to talk to little ole' me - but at least they friended me! Yay ego boost!