I'm in the process off signing up for my D license. A couple thoughts I've had about it...
First, there's the cost. The D license, a step above the bare minimum of the E license, costs about $400. Not only that, but it's two weekends a couple months apart. So I need to set aside time, and probably find a place to stay. I imagine it will only gets worse as I try to obtain the higher levels.
Next is the actual value of the course. In that brief window of time, with however many coaches are in a course at a given time, how much can they really teach you? How in depth can they really evaluate what you've learned? Can US Soccer really testify that a coach with a D license has more knowledge and skill than one with a C license? As a young coach hungry for mentors and knowledge, I'm not convinced this is the best value-for-money avenue for me to improve.
Related to my first thought, who are these courses keeping out? If the DA and MLS clubs are only hiring coaches with, say, C licenses and higher, what do those demographics look like? This seems like the same problem with pulling pros from college soccer, in the sense that you're severely limiting the talent pool.
There's a lot more to talk about on this subject, and it's been covered more in depth by people far more articulate than myself. My main issue stems from this dilemma: are these licenses supposed to be educational, or certify a 'minimum level of competence'? US Soccer appears to be positioning themselves as if they provide both, which feels to me like a difficult line to straddle.