There is a great article on this but I don't have it on my at the moment, but basically, every single Xeno game, outside of X, has existed to tell a story, the same exact story in the case of Gears and Saga, and a very similar one in the case of XBC and XBC2. X only shows those themes in its sidequests and its story never reaches the messages that every other Xeno game makes. Also, those Xeno games, Gears and Saga clearly, to a large degree XBC, and to a much larger degree XBC2, were made to be story focused game first and foremost, as in that was their intention. Obviously XBC and XBC2 are still very gameplay focused, they aren't closed to as story focused as Xenosaga, but Xenoblade 1 still is very very story heavy, and Takahashi has said that XBC2 was started in reaction to criticism of the lack of story in X.

I am not at all saying I dislike X, X is still the greatest open world to date, and the skell is amazing, but it doesn't hold up to its pedigree, or as a game in general, to the same degree as the other Blade games.