it is not likely people are going to visit from either Japan or the USA to the EU or vice-verser though i wouldn't of thought, just imagine trying to get a Gamepad through the customs in the USA, they will lock you up there thinking it's a bomb or something, the idiots.
Hardly likely. It's no different from bringing over a tablet or laptop for instance. I've brought over a number of electronic devices from the US because it usually works out cheaper and/or they are available much earlier. I've also imported through online stores lots of hardware and software both from the US and Hong Kong because its often cheaper or its something not available in the UK. Lots of people do just that and its quite common these days. That being said I'm not likely to bring over or import a Gamepad but its the principle of the matter. It's bad enough Nintendo region locks their consoles without region locking their console accessories.
Read this on another forum. Doesn't effect 99% of people so it isn't really much of an issue.
I don't know where you got that 99% figure from as its wrong. There are lots of people including myself who either bring over or import products including electronic devices, accessories and software for various reasons. The Gamepads may well be cheaper to import but being region locked even if its only regards software updates makes it less of a prospect.