1) Fear – we are afraid to teach subjects where there is a controversy or a diversity of legitimate views. Issues always have to be boiled down to black vs. white and for all else, ask your Rav. As a result, we produce students who see things in black and white, who are intolerant of other viewpoints other than the one they learn as "correct," who cannot weigh the pros and cons of issues without being spoonfed a "right" answer. You can’t reduce any discussion of Eretz Yisrael to simple dichotomies.
2) Ignorance – teachers know little more than their students about certain topics, this among them, in part because they came though the same broken system that they are now perpetuating.
3)It doesn’t matter enough – we equate love for Eretz Yisrael with love for Am Yisrael, in the sense of caring about Jewish life. That is certainly important, but that should not eclipse a discussion of Jewish nationalism as an independent value (or whether you agree with such a thing or not and why). When people talk about “existential issues” in the context of discussing Israel, they mean, for example, the threat Iranian missiles, not “existential” in the philosophical sense. Questions like, for example, whether you view the State as aschalta d’geulah and what that term means, are great for armchair philosophizing, but are not pressing for a solution any time soon, so think this tzad is right or think that side is right, it can all be cavalierly dismissed as not really relevant.