As a fake developer (i.e. PhD student in Computer Science who did very little programming) I used UML, MOFF, and other such tools extensively. I've worked on the GME from ISIS at Vanderbilt and Ptolemy from CHESS at Berkeley. The one point that my thesis advisor - Janos Stipanovitz - made brutally clear whenever we were discussing Model Integrated Computing was that the value is not in building a better IDE that makes programmers more efficient. The value is in building analyzable frameworks that you can use in safety critical systems to show that your system adheres to the safety specification that you have to meet. So, I don't think there are any programmers who would benefit from these tools, but they absolutely do benefit system engineers building fly-by-wire airplanes, nuclear reactors, Mars rovers, etc...

Now, I am starting to work on a web-ap with a designer and I find that State-Charts are a great way for us to spec out the application. We're not trying to generate code from these but my partner is such a visual thinker and learner that State-Charts are a much more appropriate way for us to communicate than a spec written in English.