you know, nintendo's main games have input from a lot of the same people. the way they're designed is mostly the same as well. there are two camps from what i can tell, and they're either koizumi/aonuma or tezuka/miyamoto.
koizumi and aonuma seem to prefer their games to be larger and sprawling, with focus on atmosphere and storytelling. tezuka and miyamoto prefer focusing much more on game mechanics- to the point where if storytelling gets in the way, then it should get out of the way. when you have two camps, and when one wins out most of the time, it's easy to start feeling like you've seen a certain type of design before. a good recent example is probably luigi's mansion and paper mario. both solved the problem of being handheld version of franchise titles the same way, with levels to be completed in just a few minutes. the gameplay is wildly different, but the design choices are generally the same.
when i played rayman 2, it was my favorite 3d platformer, and it was my favorite 3d platformer for a long time... until mirror's edge, or so. there was just this feeling i had about that game i couldn't put my finger on. when i played beyond good & evil, into the first hour of the credits, that same feeling returned. i even remarked to some people here that the last time a game elicited this weird feeling out of me was rayman 2. at that time, i had no idea michel ancel was the director of both.
and i don't think it's limited to nintendo. i personally don't care for sony franchises. sony has a tendency to push a design philosophy i care very little for, which is making their games as immersive and cinematic as possible. generally, i feel you lose a lot on the game mechanic side when you start pushing the background elements more. they don't make bad games (unless you're david cage), but i don't get excited for god of war or uncharted. despite being in very different genres, they seem so very similar to me, and as a whole, uninteresting. i still buy and enjoy some of their first-party titles like littlebigplanet, and i'm looking forward to the last of us and the last guardian (when i get my ps4 in 2016), but nothing they make will have me rushing out to buy a console. so for me it's easy to see why someone would think the same of another company that dabbles in many different styles and genres.