I'm pretty conservative when it comes to prayer and ritual. We Jews have plenty already, and -- for tradition's sake if nothing else -- learning to appreciate existing prayers and rituals seems a better use of energy than inventing new ones.
Nonetheless, there are occasions on which innovation is required, and to suggest that new rituals cannot be accommodated strikes me as absurd. All Jewish practices were invented by human beings at some point in history. When did the rules change?
Equally absurd is the practice of some Orthodox congregations to accept new rituals and prayers while making sure to indicate, in some way or other, that they aren't "real." God's name is deliberately avoided in the composition of new prayers, and acts that are normally accompanied by blessings are performed without. On Yom Ha-Atsma'ut, these congregations recite a selection of prayers without God's name, and/or recite Hallel without a blessing. Some even read from the Torah and Prophets without reciting blessings, presumably because they aren't really reading, or it isn't really Torah. Or something.
One of the wiser decisions of the Conservative movement was to model Yom Ha-Atsma'ut observance on the two other post-biblical holidays, Chanuka and Purim. An al ha-nissim prayer is inserted into the Amida and birkat ha-mazon, thanking God for another act of redemption. Hallel is recited in its entirety, accompanied by the appropriate blessings, as on Chanuka. A selection from the Torah is read, with blessings. (Okay, so they added a haftara, too. There are all sorts of random haftarot.)
You're probably expecting me to tie this up somehow, but my mind isn't quite that organized. Also, I have work to do. So that'll be all. Chag Sameach.