If I came out and said "Blackearl: Your country sucks and you should move out of it", I don't think you'd think it was very helpful advice.
I think coming out to the internet, sharing some personal anecdotes about racism and personal issues, and maybe publishing problems you've experienced personally can help. Not only for teaching others about the issues you yourself face, but also for helping keep ones emotions in check and meditating upon your own issues.
Obviously, this discussion thread exists to criticize Japan and bring forth issues. But in order to be more helpful to everyone involved, its more beneficial to be more specific about what can, and can't, be done to fix certain issues.
With regards to your specific point: giving up because of cultural norms is defeatist and doesn't seem helpful in any case. Now I'm not Japanese, nor have I ever been to that country. But it sounds like Japan is a functioning democracy, so publishing opinions and raising issues is definitely the way to move forward in that kind of political system. The people must be aware of a problem (and agree that it is a problem) before you can ever hope for the politics to change.