Holidays that aren't celebrated worldwide (such as Cinco De Mayo) will not have anymore stock in Onnet Town anymore, however you might be able to win some event hats related to those holidays.

As for things such as the gallery, it was pretty much dead. One of the main problems with iClassic is that the gmap is so small everyone hangs around in Graal City, leaving places such as the gallery, swamp pet room etc. a dead area, so it's better off to just remove those places and focus on other things.