Well, it is a loss for us, but unfortunately it's just not technically feasible to have a global seamless login experience yet. We're working in that direction.
> users who browse but never vote or post just aren't really that valuable, relatively speaking – except to encourage cross site discovery which we intend to incentivize in other ways.
and for the behaviour I desire I fit exactly the mould of a user who isn't looking to vote or post. Okay, I might vote on the excellent responses, but on the sites that I just want ?tab=week or ?tab=month behaviour from, I don't want to ask questions.