Let's look at this from a different angle... What if Apple already has a super cool headphone based wearable tech.
Maybe Apple RND came up with something like "Google Glass minus the visor" a while back. That something could well look like a chunky set of headphones, right?
Now let's take a look at the current wearables market... The high profile items are things like Glass, Pebble, Samsung Gear. And they're almost all painfully uncool (outside of Sillicon Valley, anyway).
If Apple were going to launch its chunky iHeadphones, it would know that it'd be up against the "dork factor." So it would make sense to spend some cash to negate that. If so, purchasing the coolest headphone manufacturer you can find, and tying their brand to your upcoming tech, makes a lot of sense.
While I applaud your imagination, this seems to go against Apple's vision of elegance and miniaturization (i.e., the perfect technology is invisible).
And then patent the idea:
Claim 1: Headphone connector means comprising a plurality of means that are incompatible with all other brands of means
If "Beats Suck" turns into "Beats are Really Good, and Less Expensive", then they will lock up a good deal of the higher end headphone market.
There may also be some interesting exploration of what's possible with a headphone-based wearable. Plenty of room in that particular fashion accessory...much more so than in a watch.