Should Jews abandon the second day added to festivals in the Diaspora?

The Torah describes Rosh Hashana and Shemini Atzeret as one-day holidays, while Passover and Sukkot are to be observed for seven days. But 2,000 years ago, an extra "second day for the Diaspora" was added to most Jewish festivals outside Jerusalem, to ensure that even if distant Jewish communities missed the day the new moon was declared - the traditional start of Jewish holidays except Rosh Hashanah, which falls in mid-month - by observing each festival for two days they would ensure they wouldn’t miss the "real" day. Even when the Jewish calendar was fixed by the fourth century CE, the custom of adding one extra day to holidays persisted. Yom Kippur was the only exception, because adding an extra fast day was considered too much of a hardship.

When the State of Israel arose, the extra "Diaspora day" of festivals was no longer observed in the new Jewish State. Reform Jews outside Israel also abandoned the extra day, both in solidarity with Israel, and because they no longer believed they were living "in exile." Most Renewal and Reconstructionist Jews followed the Reform lead, while Conservative and Orthodox Jews outside Israel continue to observe the extra days. But now that so many Jews travel back and forth to Israel, there are no hard and fast rules. The Talmud suggests following the practice of the place where you are located when the holiday falls, and many Jews visiting or living temporarily in Israel indeed follow the shorter Israeli custom, but Orthodox and Hassidic Jews visiting or living in Israel usually preserve the Diaspora practice of adding a second day, out of respect for their tradition. In contrast, some American Jews who used to live in Israel are carrying the shorter holiday observances back to America with them, as a statement of Zionist solidarity.

Now that Israel exists, should Jews worldwide abandon the extra "Diaspora" day attached to Passover, Sukkot, Shemini Atzeret and Rosh Hashanah?