I probably get a PR pitch every other day for some webinar or conference about selling to Millennials or marketing to Millennials or whatever to Millennials. We're definitely at the peak of some sort of Millennial overload.
Millennials are just at their moment in the marketing spotlight. Happens to every generation. As a whole they're at the traditional age when they'd be forming brand affinities which would last a lifetime, so companies are after them.
I'm not sure it works that way any more, but I'm also not sure it doesn't.