maybe to you it doesn't matter, but these things can be intensely personal to people. it's still an issue of violating your space (to the layman end user, i know the technical definitions of "your space" are nebulous, im talking about the emotional ones that i think posterous is kind of violating).

and what happens when the idiot who posts the nigerian scam on your blog scams your mother who is reading your blog and assumes it's from you? no big deal? move on with your life? try and be a little imaginative with the things that could be done here...

if it's not a big deal, posterous should make it clear to users what they give up for convenience. again, i really don't think users would make the same choice they are to user posterous if they understood the implication. whether or not it matters to you.

and more importantly, there are a ton of people suggesting pretty viable alternatives that wouldn't make it harder to post and would still allow a lot more security.