hashkafah philosophy - Why does the belief in Mashiach require that one be anxious for his coming?

The question of why belief in Mashiach should be a fundamental belief (an ikkar/yesod of Judaism of the Rambam's 13) is asked here, and I answered it myself here.

However, when it comes to this particular belief, the Rambam in Hil. Melakhim 11:1 adds that merely believing is not enough:

וכל מי שאינו מאמין בו, או מי שאינו מחכה לביאתו, לא בשאר נביאים בלבד הוא כופר, אלא בתורה ובמשה רבינו

and whoever doesn't believe in him or doesn't await his arrival denies not only the other prophets but the Torah and Moses our leader

and in R. Kapach's translation of the Rambam's 13 principles (in the intro to Cheilek), the Rambam adds that one is required "להתפלל לבואו", to pray for the coming of Mashiach.

Why should one who doesn't actively anticipate the coming of Mashiach be considered a heretic? Isn't it possible for one to completely believe בתורת משה רבינו, the Torah of Moses our leader, but still feel so comfortable in the diaspora/exile that they aren't so anxious for the Mashiach to come?

Answer

An excerpt from Fundamentals and Faith (based on teachings of R' Yaakov Weinberg, written by Rabbi Mordechai Blumenfeld):

It would seem, then, that "awaiting him" should be understood as attributing to him so much importance that one is aware of missing something, of lacking something every moment of one's life. It is not enough to know and believe in his coming; one must also feel and understand what it means not to have him in our world. A world without the Messiah is a world of exile, where Jews find themselves dispersed amongst many nations. It is a world where even in the Land of Israel, Jews are subjected to the whims and values of other nations. It is a world in which terrible barriers created by spiritual apathy deter man from coming close to the Almighty, and where the opportunities to approach Him and to experience His presence in His Temple are gone. There is no greater destructiveness for the Jewish soul than to lose the awareness of the bitterness of exile. Once one appreciates that the meaning of life is determined by how close one comes to the Creator, the loss of His presence becomes an acute, intolerable pain, a cancer, which eats away at man's spiritual core, which can only be anesthetized by distracting ourselves through all kinds of self-delusionary pleasures. In doing so, mankind has become callous and his senses have become dull to the ultimate pleasure this relationship would offer.

There is no greater destructiveness for the Jewish soul than to lose the awareness of the bitterness of exile.