the only people who benefit from the current pricing model are registrars.
if domains cost $300 a year we'd have less than 1% of the number we have now,
but the ones we have would actually get used. i have never received mail
from a domain ending in .biz that was not spam, for example.
while i worked for neustar when they were proposing .biz and .us, i didn't
know what a bunch of idiots and crooks the management are. they do run lnp
and you can look for spam on your tone too courtesy of the lnp dip operator.
the current pricing model is $6 to vgrs and its successor in interest,
afilias, plus two dimes to icann, and the rest to registrars. some have put
their price point down to sub-dollar.
the interesting tidbit from the gmail launch was the $2/gb/yr costing that
google published. the recurring cost to the db operator for store of what is
a sheet of paper is well under $6/yr/sheet.
with fewer than 10^^8 total registrations, and five registrars with most of
the total volumn, most registrars must have fewer than 10^^6 registrants and
make a business unit (meet ongoing icann fees and per-registry fees), etc.
the price point for .coop domains is higher, i've yet to get spam from any.
there are other ways than pricing to drive down the number of domains and
drive up the use of the remaining domains. until recently to get a domain
in .cn one actually had to touch paper in the prc and meet some sanity check
for allowed use.