Because that's a stronger claim -- that it is the future of Dance music for everyone.
> why does it have to be "if you're a Nerd".
Because with that qualification, its a weaker claim -- for the rest of the universe, it may not be the future of dance music.
Or maybe they mean, what nerds think the future of dance music is.
By claiming "if you're a nerd", they're creating a class distinction where one group can and does ascertain truth, while the "others" cannot and will not.
So not only is it the future of dance music, but you'll only know if your privilege and knowledge can allow you to. A modern day hermetics of sorts.
But you know, thats just, my opinion man...
Yes, it is.
> Either it's the future of dance music, or it's not.
This statement excludes many possibilities.
> The future of dance music is the same for everyone.
This is not necessarily true. Different subcultures can, and often do, have different dance music. Its quite possible for the "future of dance music" to be different for different subcultures.
EDIT: Though, there are multiple different plausible interpretations of "This is the future of dance music (if you're a nerd)", and I've been focussing on the interpretation that could be rephrased as "This is the future of dance music for nerds".
Other possibilities include "This is what nerds see as the future of dance music" and the distinct-but-closely-related "If you believe that this is the future of dance music, you must be a nerd".
In those other cases, its not a weaker claim but a completely different claim than the plan "This is the future of dance music" claim.
Nope. Dance music has what we call "genres" (and target groups).
Nothing will be the future of ALL dance music, except if all people decide to adopt one dance genre.