I disagree with 1 as a blanket statement.

There are technical reasons to consider, as well (yes, it's DNS again). If you want to receive emails @foo.com, you have to set MX records for foo.com., and that means you can't set a CNAME anymore - you'll have to make do with A/AAAA records.

For a lot of applications this is not an issue, but it does mean an overhead for highly distributed services. You won't see many global/high traffic companies drop the benefits 'www' gives. This is not purely to get the 'old folks' market.

(PS: The subdomain doesn't have to be www., of course - cnn goes with edition.cnn.com., for example.)