I don't think Kant's theory looks bad to people except insofar as they have misunderstood it (for instance, as heartless and ironheaded, or as committed to an absurd metaphysical conception of freedom that violates Kant's own philosophy).

We cannot predict the effects of our actions, especially our collective actions over generations or centuries, to use instrumental reasoning toward these big final ends to tell us what we ought to do.

Popular religion since the time of Kant and Fichte has gone in a direction they tried to prevent and that has been disastrous for the humanity both of believers and of the rest of us. Look at the role of religion in Republican presidential primaries if you need any confirmation of this last statement.

What I most fear now is that within a century or so there may not be any human future at all.

We can establish empirical criteria for free actions, and investigate human actions on the presupposition we are free.

What are we to think of the shortsightedness of the great mass of people who are content to do nothing about it, and even worse, the greed or venality of the rich and powerful who deliberately bar the way to human survival?

The problem I see with utilitarianism, or any form of consequentialism, is not that it gets the wrong answers to moral questions. I think just about any moral theory, worked out intelligently, and applied with good judgment, would get just about the same results as any other.