Like many people, I am currently knee-deep in Persona 4. And like a very large subset of that already sizable group, I played through Persona 3 in August of last year. Persona 4 borrows a lot from it's older brother - really, it's almost the same game. A few improvements have been made, but besides the tweaks to the battle system and scheduling of the game, it's another chapter in the Persona 3 saga with arguably better pacing. The game even reuses most of the enemies and Persona from the previous series entry and even, at one point, its locale. Despite these similarities, the game is garnering praise from all around. I've yet to meet one person who considers the game to be derivative or lacking in originality - if anything, people are focusing on the tiny tweaks.
Compare this to another late year release: Gears of War. Sure, the game has received tons of praise. It's still an excellent game. But if I ever heard one complaint, it was that it was "too much like Gears 1." In several reviews it was pretty clearly stated as a negative that the opening of the game felt like the first game to a fault. Devil May Cry 4 is another 2008 game that lost points for being derivative of the third game. On the Wii side of things, Animal Crossing: City Folk experienced the same criticisms. Every gamer can list a few games they dislike because they feel they lack originality.
All these games have something in common that Persona does not - they were released more than two years after the previous games in their respective series. On the other hand, a game like Persona 4, released just over a year after Persona 4 (and only months after FES, which is how most experienced Persona 3) hasn't garnered a single complaint of repetition in the critical sphere. Another example is Uncharted. It was called "Gears of Tomb Raider" in more than one review, but less than a year after Gears of War came out the idea was still fresh. The idea of the expansion pack is the same: more of the same, before the idea gets stale in the mind of the player.
What does this mean? Really, not much; it's obviously impossible for companies to release games every year to capitalize on the ideas of yesteryear. I just found it interesting to note that gamers don't hate unoriginality and any sense. Moreso, there exists an expiration date on a good idea. Why is it that a game released a year after the last one is fun and new, while a two year gap leaves some people thinking "same old"?
[Haha have to leave publishing blog without editting or images have fun gl dd]