VB/HH are lower for several reasons.
1) they are off wdw property and real estate rules apply ("location, location, location"). sure, in some cases (probably moreso during the current economic situation) you can still find room onsite at wdw at the 7 month window...but is it going to bother you if you get locked out? there is a real risk there.
2) annual maintenance fees are higher at VB/HH. so you'll pay more over time in dues than if you owned at an onsite resort.
2b) being on the coast, VB/HH also have a higher risk of storm/hurricane damage. VB owners were nearly charged a special assessment to repair storm damage a few years ago. (insurance wound up covering it.)
3)
much smaller risk: if
DVC decided to spin off any of their resorts, VB and HH would be two of the most likely candidates. this is unlikely to happen, IMO, but if it did, you would most likely find it much more difficult to trade for an onsite property (if not impossible) and the value of the properties would most likely decline a lot farther.
for some people, the lower prices make it worth rolling the dice a bit. many are ok with booking whatever is available at 7 months onsite (usually larger resorts like SSR or OKW) and waitlisting if necessary.
with prices for SSR and OKW being awfully reasonable, i'd prefer to have access to wdw at 11 months...YMMV.