You're right, but sometimes it's just a bit of greed on the part of the seller. I had a deal fall through yesterday. The house is nice, but the comps aren't there to justify the price and the sellers won't go lower to be more in line with the appraisals. Unfortunately for people in that situation, no bank will loan more for a home than an appraisal says it's worth. Plus, in MOST markets, smart buyers who can come up with a good down payment, won't pay more than the house is worth either.
I expect you will be seeing more of this in the next years time.