Yes, we probably are condemned. For the same reason that mathematicians are condemned to know how to add and subtract, even though one could achieve the same results using a more general method.

Monospace is just simpler. We use it in consoles, and they aren't going away or being revolutionized. And if you want to write a new text editor, you will probably end up supporting monospace behavior before proportional simply because it is such a simple and flexible algorithm.

And in the end, the only reason to use proportional font is for style and a marginal increase in readability.

So it's not a matter of laziness, but of efficiency and design fundamentals.