Well according to Berman, they were only given a short time to come up with a story and get it filmed, and they also were not given a two-hour finale, only one. Still, they needed to write the thing, get TNG costumes made, build TNG sets, have a CGI Ent-D and asteroid field created, and get a bunch of alien makeup and wardrobe stuff made. I'm not sure what the status was of the Ent-E sets and costumes from Nemesis, but if any of that were available (including the Ent-E model which could have stood in for the Titan), wouldn't it have made more sense for the finale to be post-Nemesis Riker and Troi? It sure would have saved them a ton of money and time.
Here's a scenario: Riker, Troi and the Titan are in orbit of Romulus post-Nemesis, working with the government to sign a peace treaty. During this time, it is revealed that the wreckage of the NX-01 is on Romulus, including its flight recorder. Riker and Troi use the Titan's holodeck to recreate and observe the last moments of the NX-01 and her crew, which up until then was a complete mystery. They are simply observers, not engaging with the program in any way, nor is the story about Riker. It's a faithful representation of the last days of the ENT crew based on the flight recorder info. And all of the cast dies in a dramatic way, not just some ham-fisted crap like what happened to Trip.
Wouldn't that have worked better? And it took be about a minute to write. Plus, it also even gives closure to the 24th century post-Nemesis.