C.E. Evans said:
To me, Nemesis was the opportunity to return the Romulans to being the bad guys of the Star Trek Universe--the enemy the Federation was most likely to enter a full-scale, all-out war with.
Instead we got Star Trek: Attack of the Clones with Remans getting more screentime than Romulans.
Nemesis should have been a no-brainer, a straightforward, no-clones or Remans allowed story about Picard and the Enterprise facing their equals in the Romulan Navy. If anything, Nemesis could have been simply a super-sized sequel to TOS' "Balance of Terror" or TNG's "The Defector" the same way TWOK was a sequel to "Space Seed."
But it's always easy in hindsight for someone to say "what oughta been done."
At this point, however, I don't think a Romulan movie is possible. Unless it's a movie about a full-out, "I ain't playing with you, fool!" Romulan attack on the Federation, any such movie probably runs the risk of being too much like "Nemesis redux"...