True, I took the old one... But here there you also have the exception. There are situations in which it is legal to not send a fqdn... I know of some mailservers (that I leave unnamed ^^) that don't send a fqdn because they belong to a lan and don't have a reverse domain entry. Seems to be standard practice for small office setups. Or maybe it's just a large regional company that gets it wrong...
It is true that you should always do that, but the reality looks a bit different. The question is what the ispcp team thinks would be the best default config for the admin that doesn't check everything as he should. And be it just to prevent them from spaming the forums/ticket system