I would argue that it doesn't make Fallout 3 less "Mature", it makes it less "Serious". And that, I believe, was exactly the intent with the retro-futuristic theme.
Yeah that was kind of the message I was trying to get across, people tend to interchangeably use the words mature/serious as an age audience with games, serious games are for grown ups, whereas non serious are apparently intended for teens (peoples views are obviously subjective).
My point was that in comparison to the others, I thought Fallout 3 was more serious natured in comparison to the two previous games, and obviously that was Interplay's intentions all along, infact that's what they're trying to promise with the fallout mmo, a world of black humour filled with murder, six and drugs.
Gore can be serious, and it can be used as a means of shock humour (bloody mess), I'd like to see an amount of gore in Skyrim, but not an extensive amount, maybe just finishers + explosions would be enough to satisfy my bloodlust.
Traps would also be great format for gore, I found them lacking in oblivion but maybe a rogue based class could plant trip wires to trigger one of those impaling traps that swing around and happen to catch you in the chest, ala Apocalypto, or a mage setting a fire trap on a door/chest that explodes when used.