And of course there's the matter of Ro being, you know, the insubordinate type who got eight people killed. Can you blame Riker for being a bit standoffish to her? You heard the exchange between Riker and Picard (before Ro ever came aboard) - they were going to give Ro extra scrutiny, from the get-go, because of her previous record. As is their right, as Ro's commanders.
The simple fact is, Riker GETS to have an attitude. He's the senior officer. Ro's the one who's supposed to know her place and show proper respect and deference to HIM, not the other way around.
This is why Worf gets to wear the baldric - because he respects the chain of command, and treats Riker (and all senior officers) with the respect they deserve.