Other reasons to know the intermediate stop point -

1) On the schedule board, flights are listed by the first destination. It's a lot harder to find your flight if you don't know the intermediate stopping point.

2) At the gate the first (and sometimes only) departure city listed is the next immediate stop.

3) The on board announcement says you are going to the first stop. In order not to panic, it is nice to know you are on the right plane.