I came across the slogan »Proud not to be proud.« recently and really like it. I really like Germany and am glad that I can live here. But for me being proud has a lot to do with personally having done something for the thing to be proud of. I have zero stakes in the beautiful landscape, my influence on the society, economy and whatnot is negligible. Why would I be proud of the country? I also think that nation states are probably not the best way forward but that will take us to far now.

Pride in personal achievements has a catch: it's only available to those who actually did achieve something. Those who did not still have a desire for pride and "group pride" (be it national, ethnic, religious, supportership of some sports team or even just membership in some specific profession) fills that gap.

As much as i despise patriotic displays, i still think they can offer great value as a lesser evil when even more dangerous group pride identities (e.g. religious or ethnic radicalization) are just waiting to fill the gap for those in need. Not only the american, but also the french or british group identities are much more accessible than for example german (much of national identity defined by difficult relationship with history, newcomers don't share that heritage) or belgian (much of national identity defined by being of either flemish or wallonian ethnicity, newcomers are neither).

Some Americans agree with you: https://www.youtube.com/watch?v=mIG4-03Gru4

Patriotic displays were one of the major tools that enabled WW2. Maybe not as a cause, but certainly as an absolutely required component.

We frown upon these things not because of what happened, we frown upon them because of what we don't want to happen again. The past might be long gone, but the future is always right around the corner.