I've never thought about it before, but I think you've hit the nail on the head for explaining Wolverine's popularity - he is nostalgia, and when it that not popular?
I've always found his relations to Japanese culture to be very strange since you're right, he doesn't fit modern Japan at all, but he does fit into the older, traditional nostalgia of Edo era (or before) Japan. There's a reason why the comic I took my icon from made the idea of Logan as Lone Wolf so plausible. (Incidentally, if you haven't read Lone Wolf and Cub, you'll love it.) I have a hard time reading Wolverine's Japanese scenes because part of me is always crying out that the Japan he's in is already dead. Of course, this is comics, and it's no fun to write about the fact that there are no ninja clans left or that you have to search pretty hard to find a proper tea ceremony...
I may be commenting simply because I have the perfect icon for this...;)
I've always found his relations to Japanese culture to be very strange since you're right, he doesn't fit modern Japan at all, but he does fit into the older, traditional nostalgia of Edo era (or before) Japan. There's a reason why the comic I took my icon from made the idea of Logan as Lone Wolf so plausible. (Incidentally, if you haven't read Lone Wolf and Cub, you'll love it.) I have a hard time reading Wolverine's Japanese scenes because part of me is always crying out that the Japan he's in is already dead. Of course, this is comics, and it's no fun to write about the fact that there are no ninja clans left or that you have to search pretty hard to find a proper tea ceremony...