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.)
Yep. The DNS hierarchy exists for a reason, and if you have a bunch of machines, you want to use it.
Also, I'm a single person, and I have multiple independent web sites. Many of them live under the same domain. Lots of companies have many more. You can play annoying tricks to smush them all into a single name (at least, most of the time), but why?
I think the world is ready to internalize the idea of hierarchic names, at least insofar as understanding they're independent entities grouped under the same name. Haven't seen any studies, but it seems like we're past the 'do I need the "www"'? point.
All that said, I also like short. The magic comes from knowing when to choose what, and I don't think you get there with rules-of-thumb alone.
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.)