I too, laugh when people say the Wii and DS are "family friendly", albeit for slightly different reasons. As for the Wii and DS having a small number of M rated games out or coming out, it doesn't really signify a shift in Nintendo's strategy. They had a handful of exclusive games for the Gamecube (Killer 7 for example) which were M rated.
Truth be told, I'm not finding the Wii all that family family (or the DS for that matter). When you're trying to share your hobby (gaming) with a 5 year old boy, a 6 year old girl and a 7 year old boy, it's very difficult to find the right games. I want something that they can play independently - solving puzzles on their own, competing against each other and working together as a team. So far, one Wii game has delivered on that - Mario Kart. They're not very good at it, but they have a ball with it.
Being the Wii, I figured I'd try some more kid friendly fare - but it doesn't work. The shovelware games often have kludgey controls and are difficult for kids. Thinking back to recent purchases - Super Smash Bros. Brawl was a bust. Endless Ocean was high on my list - a chill out kind of game, and teaches them about sea life at the same time. Nope, they didn't take to the mechanics at all. I've rented myriad Wii titles from Gamefly, and they miss the mark frequently.
Case in point, for a comparison, I rented Monsters Vs. Aliens on the Wii shortly after we rented the same title on the 360. After 1 hour long session, the kids wanted nothing to do with the Wii version and actually asked to play the demo on the 360 instead!
Now, I'm migrating the kids more to the 360. We had fun with Monsters vs. Aliens, Puzzle Arcade is a sleeper hit, You're in the Movies is a family friendly hit that the kids go ape for. The controls are more intuitive and less "wonky" than arbitrary, tacked on motion controls that actually take away from the game.
I don't like the DS, because it puts the kid's attention on one small area. At least with a console, you're watching them, having fun with them, seeing where they're getting frustrated so you can call an end to the festivities, or lend some help. The DS is far too isolationist, and I notice the kids seem more "zombie-like" after playing that for an hour than they do playing on a console.
So, when people make a fuss about the Wii and DS being family friendly, just because they have a ton of games with cartoon characters doesn't mean that there is actually family enjoyment coming from them.