AFnord: I can only speak from my own experience here, but I play hex based tabeltop wargames (World in Flames, advanced squad leader and Lock 'n load), and when suggesting that we should get some non-WW2 non-Vietnam games to play, I was met by people saying that they would mainly be interested in playing games about wars that they are more familiar with. Heck, it can even be tricky to convince people to play games based on lesser known parts of WW2. And while there certainly is a niche market games based on less well known conflicts, the lesser known the conflict is, the more niche the game becomes.
Most people (probably the vast majority of them) who play hex-based wargames are history geeks.