Re: Why didn't Picard know Sito Jaxa ['Lower Decks'] was on his ship?
I think Riker's role is one of the strengths of TNG versus TOS. In TOS, it's barely hinted what Spock's responsibilities as 1st officer are. It's clear in TNG that Riker has day to day responsibility for running the ship.
Another difference between the two shows is the size of the ship. The Enterprise-D was much larger and had more officers than the TOS Enterprise. Riker is effectively the staff captain on a ship that large.
~Tighr™: Not helping the situation since 1983