Thanks for bringing this up.
Yes, we should care about usability.�
And I agree that usability is attainable as long as you approach it with consistent discipline. It's similar to designing code: you start asking questions, figure out what the right questions are, and then stick to it.
I like Steve Krug's Don't make me think book. However, please keep in mind that the lessons in the book apply specifically to the web. An environment like Pharo should not obey exactly the same things.
But, as Esteban says, let's focus on the future, and keep usability high in our list of concerns. Even if we might not know how to do it now, simply sticking with it will make us better in the long run.
Cheers,
Doru