At Fluxitek, I am involved not only in the design of the overall user experience, but also in implementation. The temptation to skip UX work is sometimes great for our team.
So: I, too have to keep convincing myself why usability work is absolutely crucial to our product success. I’m now trying to find a succint enough way to express the basic needs for the work.
This is what I’ve got now:
Software engineers often question the value of usability work, i.e. verifying assumptions in user testing. And indeed, it may be that a good designer could design a UI that does not create major confusion for most. That is, if they already have lots of experience from usability testing in other projects, and if the domain is not novel.
But note: In any application that is done without explicit user research and usability testing targeted for the specific UI, you still tend to have dozens of small confusing moments that make up the overall user experience and lead to a general ‘yuk’ reaction. Even if the app generally “works” or “meets requirements”.
Not to mention that if you don’t intimately know your users’ goals, you are likely to be designing the wrong overall application.