OK, well I have to say that is really lame. If they want it, they should ask for it.
Anyway, this now reminds me of another inconsistency: in the I-129F form it says that you can send photocopies of everything, however, posts from here and elsewhere indicate that you need original signatures on all of your documents. The amount of space they allow for e.g. full name and address of employers is way too damn small too. The whole form in general seems like it was created by someone who doesn't know what they're doing. ("Look ma, I made my first PDF" ... etc)
Zadan got a reaction from JonasyAbe in beneficiary birth certificate required for I-129F / K1?