The problem is that while a lot of music (I'm thinking mostly of pop and hip hop here) that's geared towards teens and adults also appeals to kids, it's not actually appropriate for them. So what's a mama (or papa) to do when they want to rock out, but not expose their kids to music and musicians they're just not old enough for? Thankfully, besides the classics, there has been a lot of kickass kids music coming out lately. Perhaps a lot of musicians have become parents themselves and realized the lack of quality kids' music? Regardless of the reason, there are now many options to choose from beyond "The Wheels on the Bus."
I'm not a fan of McDonald's for a variety of reasons, but beyond their tasty unhealthy food they are a perfect example of how marketing has changed over the years to further push gender stereotypes upon consumers.