They have been popular for a few years now. Whether or not this is the work of the 'higher-ups' or a reflection of the current generation mentality.. I do not know.
Desensitization perhaps?
This links in with your 'goth and gaming' comment. Although the 'goth' culture does not directly relate to gaming, in fact see here:
http://news.bbc.co.uk/2/hi/health/7621412.stm ), it is true that a major proportion of games are clearly violent. Here perhaps it is not only desensitization but the promotion of a killing mentality? To dumb-down the masses?
(I was an avid gamer - hundreds of titles played, even wrote reviews - and have links to the game industry through several projects.)