Israel at 57: the political side vs the religious side

Yom Ha'atzma'ut was observed this year on Thursday 3 Iyar rather than Saturday 5 Iyar because the Knesset said so. Perfectly reasonable for a national legislature to set the date of a national holiday! But I'm not so hot on the idea of a legislature setting the date of a religious holiday; I would not approve if the US Congress decided to move Shavuot. I don't know whether I observe Yom Ha'atzma'ut as a religious holiday, which de facto means that I don't, but I am mystified by those who observe ritual practices (e.g. hallel) on this day and are willing to move them by order of the Knesset, a secular body, most of whose members are secular Jews or non-Jews. But I guess a lot of these people have ideas about church and state that differ from mine.

I understand not wanting to do fireworks on Shabbat, just as megillah reading, matanot la'evyonim, etc., are moved to Friday or Sunday when Shushan Purim (15 Adar) falls on Shabbat (like this year). But even in that case, the liturgical aspects of Purim (al hanisim, vayavo Amaleik) still happen on 15 Adar, even though it is Shabbat.

Also, among those who observe mourning practices during sefirat ha'omer (which I don't, so this is a moot point for me), many of them suspend these practices on Yom Ha'atzma'ut. Therefore, actions that would otherwise have been forbidden to them (i.e. anything they don't do during sefirah) were considered to be permitted on Thursday 3 Iyar, because the Knesset decided that this was the date of Yom Ha'atzma'ut. What is the possible logic behind letting the secular Knesset rule on matters of issur v'hetter?

Once again the ends of the spectrum meet!