Dear Rabbi: In the Jewish diaspora is a problem when a Jewish holiday, for example Shavuot, falls in the middle of the week. One cannot go to the university and at work one has to ask for two days of holiday. Is it not the time to change that rule that and to unify the Jewish People?
Uniting the Jewish People is a worthy aspiration - one that is repeated three times daily in the Shmoneh Esrai prayers with the call on G-d to "gather us from the four corners of the earth". As long as Jewish communities continue to exist in the Exile, the laws of the exile apply - one of them being that a festival includes a second day of exile. One can see this as a reminder that the sanctity of the holiday that is concentrated in the Land of Israel - the natural home of the Jewish People- is more difffuse in Exile; you need two days to even approach the same results. Chag Sameach and may we all celebrate together united in Eretz Yisrael.