Their marketing is definitely skewing younger than it did for a while, although waaaay back when, MAC was the most adventurous brand out there (more in a camp/drag/rave glamour way than just straight teeny bopper, though).
Interesting fact I got talking to to some longtime managers: The actual largest percentage of MAC customers as of last year, are women in their late 30's and 40s. I supposed they're all women who started out with MAC in their teens and are still brand loyal.
I think all this youth marketing is more to try to bring in a new wave of younger customers who hopefully will turn out as loyal as the women who are still coming back time and again for basics and perm favorites. Also, let's face it, there's so much retro stuff out there that reminds us older gals of the 80's and 90's in the LE collections - I bet it's very appealing to the customer base just out of nostalgia. I sure bought Hot Chocolate because it reminded me of a color I had way back when.
Whatever MAC is up to, I'm sure it's been strategized long term, that's for sure - EL is run by some real savvy folk all around.