Well that's just nifty dandy.
The year I quit gym because it was no longer required in middle school was the year they put DDR in place, but it was only a 'if you're good' type of thing that wasn't set up very often... I think a lot of schools are still apprehensive about it because it's a video game, and most often, all they ever see played are songs like Butterfly on Beginner mode, haha.
As annoyed as I'll be once a majority of school kids will be so excited, "Oh em gee, guys, I can pass Kick the Can on Standard!!!" and make it seem like a decently big deal, I think I'm glad they're advertising the use of DDR in schools.
You won't get really anywhere with obesity if you take a class of little kids and tell them, "Okay, go run a mile!" In middle school, gym was required for two years and I'm extremely glad that class was based on completion, really, because I would have failed otherwise. I cannot run, I cannot do push-ups, I can't do much at all, haha. It was bad because they would tell us, go run a mile, go do this, go do that. And no one wanted to do it, results weren't really there... plus with it being required only 2 years, kids hated it and often would quit and not continue the third year.
In high school it got better (for me anyways,) because there were more options of classes to take for PE(even though we only needed 3semesters of it.) I was able to avoid running miles and stuff by taking the same dance class for multiple semesters. It was fun to learn and stuff, but it wasn't exactly... as rigorous as DDR on Heavy mode, haha.

If it wasn't for DDR, I'd probably be not the way I am now, haha. Me personally, anyways. Once you get to the point where you don't really move to hit the arrows... that might not work out too well when it comes to losing weight and keeping fit.
I'm doing an Independent PE Study, or whatever for my 3rd semester of PE. They told me if I could play 60 hours of DDR, I could get the credit. Easy.

I guess in short, it's good that she's pushing it. Gym class curricula often aren't fun and don't really provide results, plus with it not being mandatory for all years of school in most places, something needs to be done to help kids wanting to continue their activities after they've completed the classes. Most people learn DDR on Beginner or Light and then once they get through that, it gets more active. That generally leads to noticeable results, yeah? Plus most people think it's fun... at least somewhat.

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Clearly not as good as everyone else here. Clearly.