Western culture is far different than eastern culture.
Japanese Audiences are big into remakes of franchises. Remakes of existing games are often just as popular, if not more popular, than their predecessor. If you look at the various Megaman, Pokemon and Kingdom Hearts remakes, they all sell incredibly well. These sell incredibly well when you couple just minor changes to the overall gameplay - this arguement could stand by itself just off of Generation 1 of Pokemon, in which Japan saw 4 remakes over the course of Pokemons life, and all 4 sold incredibly well (For those unaware, Pokemon Green and Red were released in Japan. An updated Version, Blue, was made, which mirrored how the game would be released in the West, with new sprites, fixes, etc. Yellow was a remake, followed by 2 generations later, FireRed and LeafGreen. You could make the point that Johto contained a remake of Gen 1, but that was not a selling point, so Ill mention it in passing)
A lot of games from Japan play as the exact same game, in a different setting - it works because that what the culture likes. Success through iteration is how they like things. We prefer constant evolution in a franchise, or else we claim its bland and repetitive - mostly due to over saturation of like products - we dont get many Megaman clones that feel the same way Megaman does, but we do get a lot of CoD clones that feel like CoD does.
Its this difference that splits the audiences. Western Audiences generally don't approve of iterations of the same game - they tend to drop out of the public conscious. Megaman in particular is guilty of this - the changes they make to gameplay over its tenure hasn't changed much - you don't see that many new mechanics.
Now, lets compare it to a successful iteration series in the West - Pokemon. Compared to Pokemon, each Generation sees a massive leap in technology and what the game does. Generation 1 set the groundwork for the series. Generation 2 added mechanics such as Time, Breeding for different movesets (and for more of a 1 off Pokemon), type balance, and Stat balance. Generation 3 added abilities and changed the underlying engine of the entire series to make it more dynamic and have more variables. Generation 4 once again changed the engine to allow more a more dynamic approach and put the world into a 3D environment.
The only Generation NOT to do anything in terms of major technology boost is Generation 5. Generation 5 stagnated in what Generation 4 did, and is criticized for making pretty much cosmetic changes. Even for a stagnating game, it sold incredibly well, and is making major changes to the core of the series - for the first time in the series run, we are getting direct sequels instead of remakes of the first two versions, and were treated to more graphical options to make the game feel better.
Even the remakes for Pokemon always bring in new Elements, or embrace the current engine for the series, making them feel dynamic and different in their own right. Thats how successful iterations should work.
We havent turned our backs on Eastern developers, we just have different demands. Having you change the level design isn't enough for us to warrant a $60 investment. Mario Galaxy was fun - adding a Cloud and Rock suit wasn't enough to make me want to drop the extra money for the investment. If you were to improve your game, rather then just slinging out the same basic game year after year, you might win us over. Or if you do continue to sling out the same game, do it better.