Queen

The queen appeared as an important character only in the second movie of the Alien Franchise, and i can tell you for sure that an Alien movie can be very complete even without the queen. The queen in AvP could have also not been there, but that would have taken away one of the few things that were not extremely bad about that movie.

the same with ressurection

the queen was a important role in AVP as well as RES, now as for it giving "birth" or breaking free and having a temper tantrum is a different matter. anywho without the queen we will have only limited number of drones that we all so love. though i really would like to see another single drone picking off farmers kind of movie again