Depends on your threat model. If what you want to guard against is
revealing the content of the database to untrusted parties, then yes,
encryption gives no security if anonymous pulls of the entire database
are allowed. If, however, you don't care about the database content
but you *do* want to conceal the identities of everyone who is
contributing, then you want to make anonymous pulls and keyed syncs
indistinguishable to traffic analysis, and encrypting anonymous
connections is necessary for that. [To be truly robust to traffic
analysis you would have to do rather more work than just that, but
you're dead in the water if anonymous pulls are unencrypted.] This is
just the one example I thought of in two minutes; I'm sure there are
others.
zw
smime.p7s