Well, it's at least in part because European releases simply require more work; everything needs to be relocalized in your plethora of languages, while movies and games (especially old cartridge-era ones, but apparently even now to some extent if Madworld is any indication) have to be adjusted to work with your television standards.But I guess that's the problem with being in Europe, we get screwed all ends up when it comes to entertainment, whether it's release dates, or costs.
Blu-ray is solving at least some of those tech-standard problems, as I had thought the current crop of consoles did. Localization is still going to be a pain no matter what, though, as you have a minimum of FIGS to add, and that's if you're willing to cheat and leave all the English (US) text alone for the UK.