I put myself in their position, read the first two paragraphs, and gave up.
I am going on a limb by not reading the rest and saying you might have a perfectly good point, but if this letter was directed to me, I would've tossed it away after the first two paragraphs at the audacity that you had to insult me or my judgement.
Telling "me" that "I" should be ashamed of myself, and that I didnt listen, and similar things rarely ever (to my experience) would cause me to be even open to reading what is in the rest of the letter. This can apply to either a discussion in person, or a letter. Not to say this would be discarded immedietly, because out of sheer curiosity the reader might actually finish the letter. But their minds will not be open to your points as you shut the door on them pretty hard on those statements. I guarantee that as soon as they read those first two paragraphs, they will take a defensive attitude towards the subject. Defensiveness pushes excuses, which in the end are reasons (possibly poor) to why they are going to stick to their decisions.
No one wants to be wrong, and if you approach a person by attacking them (even if slightly), they might defend the point. I mean, who here has not been proven wrong and fought until the end refusing to admit it? Might have been something simple, as an option available on a certain car... or the chassi that a certain motor was available. Or something your parents caught you messing up. You didnt want the blame of being wrong, so you just shut yourself from blame and toss it elsewhere.
If they made the mistake of not reading hearing your voices in the first place, make sure that you don't slip up and have them discard their attention as well on this letter.
That being said, still on the two paragraphs that I have read, I do like how you mentioned the sacrifices that many have made to attend that meeting. That's a definite plus and I like the emphasis on it.
But as a suggestion, find things that they have done in the past to compliment them in their good accomplishments while they served the county. Emphasize those and tie it along with the reason why you guys sacrificed to much to attend this meeting. After you sang all your praises, you say that you feel like your voice (which I'm sure many others share the same) has not been given enough consideration.
Then you bring in your points.
That's my two cents. I hope you have the time to edit that (if you agree with what I'm saying) before submitting that letter.
+++1