I agree with the consensus that it is a well thought out, reasoned letter.
I agree and disagree with this quote too in part... I think that there is a difficult middle ground to hit between spelling out the problems that you think need addressing, without going on to offer constructive suggestions, and having too long a letter that they decide not to read it all. I think the answer though may not lie in cutting out content, but instead in the order of presenting it. Perhaps write the letter as more of an 'abstract', covering the basics of what you think are the issues, just the very basics of changes you are suggesting, and with regard to 'profits' comments made by others, briefly how you feel that this will help their bottom line. Beyond that, collate more in depth ideas into an appendix that comes after the letter. Reel them in with the letter, pique their interest and then have a further resource that is there with the remaining information that by the end of the letter they should WANT to read.