BelligerentGhoul and others have made valid points, about access to play such games.
I was (quite a while ago) a teenager, when the games were on the old Atari console and nothing close to modern multi-player internet-linked shoot everything in sight, but were definitely addictive, and could waste hours on them. Late nights were normal for me and that was the case for years.
Nowadays I might not fit in (30+ years their senior) with the people playing some of these high speed games (perhaps also, if I am honest, too sore a loser if I kept being shot to pieces, esp given the high retail prices of these consoles and games) but if games are played in a family room rather than hidden away in a bedroom all the time, the number of hours becoming a couch potato can at least be limited.
No, I don't subscribe to the 'hazards of war games' that some might, and do think older teens and young adults who have a few drinks and then start fights are likely to be drink (or even escapist film) fuelled rather than game-violence fuelled because they cannot get their hands on RPGs, ground-to-air or nuclear missiles!
The age restrictions are there for a purpose. I doubt any parents would try to justify a 14 yo having vodka, or playing online poker and losing hundreds of pounds, so how (apart from peer pressure) do any of you justify a really young teen having access to games which have been deliberately restricted ?
You would be angry if they were given access to 18R rated porn DVDs or violent films, or do many other things when they are years away from being old enough, so should 'peer pressure' be enough to cause you to consider these games acceptable for someone aged 14 ?
One poster has strict rules covering DS1 and DS2 where there are 6 years difference i age, and I can understand that at (say) 11 or 12, FaceBook is also an issue for many parents, but when something has an 18 rating, I should hope any parents consider very carefully before letting anyone under 16 get access.