Not all the G+ streams are empty, so that dilemma only really has one horn. Bot-posting would raise the noise floor so as to swamp the current (small) signal. Better to attempt growing the signal itself before adding in a bunch of noise that the users will have to sort through.

Now, if one could separate off each user from their bots... that would be neat. Maybe default to only circling a user, but show that they have some bots which one can also subscribe to, if one wants.