>> Prices are low and access is simple
It's like how everyone screams about being treated like cattle by the airlines, but every airline that has tried to offer a premium service across the board for a few dollars more has taken a bath (thinking especially of the experiment American did with adding 3" of legroom across the board). Customers complain and complain, but when they sit in front of that booking agent on Expedia looking at prices, they mostly buy based purely on cost and time of flight.
Same with this. People complain about privacy, but won't pay for services, so advertising is the only possible option. Let's say Google offered an encrypted lockbox for your email for a price, how many would buy? I think Google Apps signups for individuals went off a cliff once the $5/account fee was imposed for all accounts.
Same with everything now that I think about it. And I am certainly not clean in this respect... but it reminds me:
"Those who surrender freedom for security will not have, nor do they deserve, either one." -- Ben Franklin
"Those who surrender privacy for convenience will not have, nor do they deserve, either one." -- ergophobe