I was president of a local art guild for 3 years, and am now enjoying my first year of letting someone else listen to all the complaints.
We sponsor a juried exhibition every year. One thing that we insist on is that the selection of the juror(s) is final. It is natural for entrants to be disappointed when none of their works were selected, but we have tried very hard to make our members understand that a juried show is not a critique. The juror does not owe an explanation to anyone regarding their selections. There may exist shows that do include a critique from the juror to the entrants, but ours does not. This year we have had to tell our members not to approach a juror to challenge their decision, because one member did just that. This puts the juror on the spot, and they may or may not even remember the artist's work, and they may try to smooth over the bruised ego by making excuses. This helps no one, and it calls into question the validity of the exhibition and the sponsoring organization.
Speaking from this experience "on the other side" of the issue, I suggest that you not complain, nor write a letter. You may be disappointed, but even though I personally was impressed by the pieces you provided links to, still the juror may not have felt that they fit in with the rest of the show that he was curating. That's what a juried show is, by the way; it is an entity created by the juror from works created by other artists. If he feels that certain works do not fit in with his vision of the show (whether you agree with his vision or not), he will not select them, and for good reason. For the same reason, we insist that once selected for our show, the works must be available for exhibition. If the artist sells the piece, we insist that they tell the buyer that it must be borrowed back for our show. Noncompliance with this rule will result in ineligibility if future shows.
Again, I know you are disappointed, and I can assure you that if you continue to enter juried shows, you will be disappointed again. I've been rejected plenty of times! But don't let that stop you. Just take the high road, don't write any letters, but keep entering shows.
Oh, an anudder t'ing... Always take off the plastic. Don't ask, just do it. Probably wouldn't have made any difference this time, but next time it might.