The new lintian addition "missing-debian-source-format" is starting to remind me of a pestering nanny.
I use source format 3.0 only where I see a technical benefit and that - so far - is restricted to packages that use a .tar.bz2 upstream and one or two with really tricky patching requirements. It is literally one or two as well - out of 67 source packages which I maintain (more than some of those nagging me to change).
Packages for which I am upstream and all my native packages will stick with source format 1.0 - because there is no technical reason to migrate. Packages where I'm not upstream but which continue to use .tar.gz and have minimal or absent patching needs will also stay with 1.0 indefinitely. (I can't see how dpkg can drop 1.0 support, even after multiple stable releases after Squeeze.)
I've no interest in being side-tracked into a pointless "discussion" with those who have already made up their minds that nobody could possibly think that 3.0 is unwelcome or uninteresting. Nagging me won't help - I don't consider 3.0 worth using and I see no technical reasons to adopt it blindly.