Despite being nice, I think having Inter flags doesn't go with the actual idea:
Considering the fact that all of us are Inter fans (almost all!!!), Inter flags will not help the members to individualize themselves & highlight what makes them unique from others.
Since the actual concept of the club is based on openness to players worldwide, I think it's not wrong to have different nationality flags with the option to decide whether you want to display yours or not. It has all been about individuals from different parts of the world working together within a united system, & that's why I fell in love with this great club the first place. So feel free to display a flag which suits you, in order to show the "internationalness" of the forum.
As for myself, I'm not German in terms of my ancestors being German, but I live & work currently here since many years. For those of you with a similar situation, you might think about displaying a flag based on the same reason.