In some countries, there isn't a proper "national" day, and just because there's a National Feast of some kind by force of law it doesn't mean any kind of people's celebration.
Usually those days doesn't celebrate any kind of event or even mean anything, it's just a conventional date made in certain times with a clear political goal. There are other national holidays with more significant meaning. Actually there can be cases where municipal holidays are far more celebrated than national holidays.
So i can understand that celebrating the 4th July is particularly unique or the day of the German reunification.