One critique that I've never quite understood, whether it be with video games, music, or really anything else, is the idea that "sameness" is generally a bad thing. Or rather, it's not so much that I don't understand the problem, but more like it's never felt like a problem for me.
I think part of it is that to me, the idea that any given thing is similar to another is simply a statement, not a positive or a negative. To take one example, I certainly don't disagree that Skyward Sword is very similar to any other Zelda game that's come out since Ocarina of Time. I might even go so far as to call that statement of similarity a fact, rather than an opinion - Skyward Sword is very similar to Twilight Princess, and Wind Waker, and Ocarina of Time - especially considering that there's more than enough elements of gameplay that I can point to as evidence of this.
That doesn't bother me, though. And it's not a strike against the game from a critical perspective, in my opinion. Certainly, if one would rather have a new and fresh experience, that's a perfectly valid choice to make. But to express such a preference as a criticism of the game's quality doesn't really make sense.
Besides, it's not like Skyward Sword is a copy of Twilight Princess or Wind Waker. This is the other part of why it doesn't feel like a problem to me: I tend to disagree with accusations of excessive similarity. I think this has to do with what elements of my entertainment I tend to focus on.
My favorite video games are those with a good story. I can be somewhat scattered on what actually qualifies as a good story, I admit, and of course what I'm in the mood for at any given time will change. I think it's safe to say, though, that no matter how much I enjoy any given game in the moment, it will never become one of my all-time favorites if it doesn't have at least a decent story behind it.
With something like music, I tend to focus on the lyrics. To the extent that purely instrumental tracks rarely make it into my playlists. The melody of a piece might occasionally catch my attention, but the lyrics are what keep my attention on a song.
In those respects, it's effectively impossible for any one piece of music or any one game to be the same as any other. Can you imagine trying to sell a book that had the exact same story as another? I won't deny that similar storytelling elements persist between different Zelda games, but then similar elements persist across all media (TVTropes, anyone?), so if we're going to go there it's really just a question of degree.
In short, I do understand disappointment in Skyward Sword, or in Pokemon, or any other franchise that keeps repeating the same basic formula. For my own part, I certainly enjoyed playing Skyward Sword, and would tend to disagree about how similar it really is to Twilight Princess or Ocarina of Time. That said, there's nothing wrong with not enjoying Skyward Sword on account of its similarity to previous Zelda titles, as long as that's a personal preference rather than an objective assessment of Skyward Sword itself.