I got into
40k about 12 years ago, It has never felt all that British to me, it never really felt all that anything to me, it was just a game. It sounds like I jumped into the game when they were moving away from the cynical humor and trying to be serious so that may be why. I also may just have been to young to catch it, I left the hobby for about 8 or so years only getting back into it last year or so and I think now I look at it as a giant international company more then anything else.
And Bikers? Really? Is there a big difference between American and British bikers I'm not aware of? I just don't see 1%'s cooking meth during the night then waking up to play a game of Rogue Trader

, or you talking more the laid back guys who just ride bikes? I think 80's bikers and I think
MC's for some reason.