Like many other infamous UX twitter scuffles, Alan Cooper sits in one ring and Jared Spool in the other. The question is whether it is the UX designers role to make the Return On Investment of UX clear to employers. Alan Cooper is characteristically espousing the more radical and transgressive view, while Jared takes a more practical and congenial approach.
For Mr. Spool, communicating ROI as a UX designer has multiple recurring site-lines. UX leads to higher customer satisfaction and loyalty, less wasteful projects, more competitive and innovative applications, and more opportunities for leverage.
For Mr. Cooper, the designer is under no obligation to elucidate his ROI, if for no other reason than because it simply is not the designers job, its the managers (Cooper is pretty adamant about people not outsourcing their job responsibilities). Besides, a UX designers real value is in some ways inestimable and qualitative, not something that can be easily crunched into a number.
I cannot give an answer about which approach has more merit. I deeply admire Mr. Cooper's integrity and it is part of what makes him such an important voice in UX. In my day to day life, however, I tend to take Spool's advice more seriously. Maybe when I invent the next Visual Basic I'll feel more comfortable being a radical torch-bearer.