I’m not nearly as familiar as you seem to be with the writings of Aurobindo. But did he not say that human beings constitute a “transitional species”? This, if so, is at least one good reason his teachings have been so strongly repudiated by those who accept the traditionalist perspective.
It’s true, of course, that “God became man that man might become God”—to refer yet again to the traditional Orthodox formulation. It’s also true that the second of these two becomings may be said to involve an unfolding or explication of the human possibility. To make use of a distinction one finds among the Eastern Fathers, a distinction based on Genesis 1:26: man was created in the image of God, the image representing a uniquely human potential, and for the likeness of God, the likeness representing the actualization of that potential. But the unfolding or actualization in question does not turn a man into something else; on the contrary, it completes or perfects him, making him fully what he was intended to be—or, esoterically speaking, what he has always been.
Moreover—and this is crucial—deification (Christian), liberation (Hindu), extinction (Muslim), or enlightenment (Buddhist) is not something that happens to the human species as a whole or as such, as the result of some generalized natural, or even supernatural, process. It happens, when it happens, on a purely personal basis and as the result of the convergence or synergy of divine grace and human effort. “Do not be conformed to this world but be ye transformed by the renewing of your mind” (Rom. 12:2) is in the imperative mode; in other words it’s a command, which is obeyed—when it’s obeyed—freely, one human being at a time.
And let me add this: there is no reason, certainly no empirical justification, for thinking that it’s now being obeyed more frequently than it was in the past nor that the transformation is taken place at an accelerating rate. If anything, the contrary appears to be the case. Hence the “negative assessment” (your phrase) Aurobindo has received from traditionalist writers.