My point is that even if these characters act EXACTLY like they are supposed to, the very fact that they come from a totally different timeline as the TOS characters will make them feel like impostors to me.
Well if that is your standard for judging which characters are "real," then you haven't seen most of the "real" characters for a very long time.
In "The City on the Edge of Forever," the landing party saw a timeline in which Edith Keeler died alone, then they saw a timeline where McCoy saved Keeler and the Federation did not exist, and then they saw a timeline where Edith Keeler died with Kirk, Spock, and McCoy standing over her body.
It was that third timeline that they beamed up to at the end of the episode. So everyone on the
Enterprise (Chekov, et al.) was from a different timeline than Kirk, Spock, and McCoy were from at the start of the episode. (Granted, the only difference is that Kirk, Spock and McCoy witnessed Keeler's death in the past of Timeline 3, while none of them were present in Timeline 1, and only McCoy was present in Timeline 2, but still, it is three different timelines, with three different pasts, even if all the characters are the same in the first and last timelines.)
Or, going back to the "Yesterday's Enterprise" example, Tasha Yar and her fellow officers on the
Enterprise-D were as "real" as any other characters (in fact, if Tasha Yar looked in a history book, she would see that Edith Keeler died while three mysterious men stood on the side of the street and did nothing to save her). All the events shown in TOS were the past of the characters in "Yesterday's Enterprise."
When Tasha Yar (from "Timeline G") went back in time and changed the past, she created a new timeline ("Timeline H") where the Klingons were not at war with the UFP, Worf joined the crew of the
Enterprise-D, and she, the time traveler, would have a half-Romulan daughter, Sela, who would later meet Worf and Picard of "Timeline H," which her mother created. This Picard of "Timeline H," after meeting Sela, would later travel back in time to 1900 (in Time's Arrow"), where he would meet Guinan, who would later meet this Picard again in the Nexus in 2300 (in "Generations"), and then, 70 years later, she would tell Tasha Yar to go back in time on the
Enterprise-C, because the Picard and the timeline Guinan saw around her were not the same ones from the (at least) past two times when she had already met Picard from the timeline Tasha Yar had not yet created.
My point is that the "real" characters you remember from TNG (Worf, Sela, Picard, etc.) exist only because of the actions caused by Tasha Yar and the characters in "Yesterday's Enterprise." They are from different timelines, but they are all equally "real" characters. (If you choose to like the characters from one timeline, but not the characters from the other timeline, that's your personal choice, and has nothing to do with the quality of the episode or of the story the writers came up with.)
In the TNG episode "Second Chances," we learned that the Riker we had been watching all these years was actually a transporter-duplicate beamed up during a plasma storm, and the original Riker had remained trapped on the planet for ten years. They were both the same Riker, with the same memories and same DNA and same fingerprints, but for 10 years they both had lived with different experiences. Yet at the end of the episode, rather than pressing the Reset Button™ the producers allowed the second Riker to continue to live, and he would later show up on a DS9 episode. They were both "real" Rikers, and we could care about both of them, despite their different histories.
In the "Voyager" finale, "Endgame," Janeway and the crew of the
Voyager got back to Earth after 20 years in the Delta Quadrant, but then Admiral Janeway went back in time, changed the history of all of those characters, and helped the
Voyager get back to Earth immediately. So, in Janeway's original timeline, she would have been trapped in the Delta Quadrant during the events of "Star Trek: Nemesis," but in the new timeline created by Admiral Janeway, her younger self returned to Earth and became an admiral at Starfleet Command 20 years earlier, as seen in "Star Trek: Nemesis."
So, in fact, the entire movie "Star Trek: Nemesis" takes place in an alternate timeline created by one time traveler in one episode of "Star Trek: Voyager" (in exactly the same way that the timeline in "Star Trek XI" was created by one time-traveling Romulan). So does that mean you shouldn't care about the Picard and Data and Riker and Worf in "Nemesis"? Maybe in Janeway's original timeline, Data lived for another 50 years, maybe Worf was a Klingon ambassador instead of an
Enterprise-E officer, maybe Riker and Troi never got married. Who knows. (In the "Voyager" finale, we only learned the fates of the
Voyager crew, not anyone else in the Galaxy, so we don't know to what extent history was changed by Janeway.)
In other words, if the movie "Star Trek: Nemesis" had taken place in the "original" timeline, Picard and Riker would be sitting around saying, "I wonder what ever happened to the U.S.S.
Voyager 10 years ago. I guess we'll never hear from them again." Instead, we see the new, alternate timeline, where Picard gets a call from Admiral Janeway at Starfleet Command.
In the "Star Trek: Enterprise" two-part episode "In a Mirror, Darkly," we saw two hours of a story that took place entirely in the Mirror Universe, with alternate versions of the characters we knew. But, in my opinon, it was one of the most entertaining episodes of the series, and I was interested to see how Commander Archer and the other Mirror Universe characters would solve the problems they were faced with. Even though we were not watching the "real" characters in that episode, they were still connected with the rest of the "Star Trek" Universe, and in fact the episode had many nods to continuity in Trek history, even though we had never seen these characters before, and would never see them again.
So as we have seen in "Yesterday's Enterprise," and "Endgame," and "Star Trek: Nemesis" and all of the Mirror Universe episodes, we can still enjoy the story and watch the characters solve problems, even if they are different characters than those we have seen before.
If you think back to the first episode of TNG, Picard and Data and Worf were all new characters that we had never seen before, and the
Enterprise looked different from any starship we had seen before, but we still learned to care about these characters and the problems they faced, and the time paradoxes they were involved in, because the writers wrote good stories that made us care about them.
Let's give Abrams and Orci the same benefit of the doubt that we gave Roddenberry and Berman when they created the first TNG episode.
Just because the movie is about new characters in a new timeline, that doesn't mean we shouldn't care about them and their problems. Lots of people enjoyed "Iron Man" last summer, even though they had never seen Tony Stark before. That's the point of ANY movie (including the last 10 Trek movies): to introduce the characters, present them with a problem, and make the audience care about whether the characters will solve the problem.
When Marty McFly got home at the end of "Back to the Future," his mother was thin and his father was a successful writer and Marty owned a new truck. He was clearly in an alternate timeline from the one he remembered, but he continued to live in that new timeline and have further adventures in it. And we continued to care about those characters, even if they now had different histories. I think that's exactly what the producers of "Star Trek XI" are going for: familiar characters, but different. But you can still care about them.