Excellent point. Delusion seems to have found purchase in what is commonly lumped into the "Martial Arts" or classification.
I agree with sleimann. make the choice based on what feels natural for you. In practice, the sword art of Japan that i studied (Aikibudo Kobudo) was way to stiff and structured for me (and force you to be a right-handed swordsman--i'm a lefty), yet the seemingly brawly, loose, almost "drunken" styles of western MAs appeal to my sensibilities. Were I to go back and take an Eastern MA again, it would be Bujinkan or a Chinese Kung-fu style w/ weapons (sword and spear).
That said, all MAs seem to have points of convergence, and those are the foundations of importance. I was a bit better than most starting fresh on W MAs because of the exposure to Eastern MAs. And for spear/knife fighting, all the Aiki stuff made for good application in the W MA arena.
Keith