Wow, lots of negativity in response to that idea!
Yes, I am aware that A2DP degrades audio quality. As you said, most people don't do lossless anyway. Most people would never know the difference. I can't tell you how many times I notice people wearing their headphones backwards (Left earpiece on right ear). Also, most iPod users are using the cheap-as-h*ll white earbuds that come with the iPod, which sound terrible. However, for "most users" they're just fine. Most people just don't know any better.
As I said, for people who work out with their iPod, it could be a very useful feature. If you're running on a treadmill, I don't think you're going to be too worried about havign audiophile-grade sound available while you run. You're more likely to want something to drown out most of the ambient noise of the gym and give you something to focus on.
Sure, if you're sitting at home or in a studio, you're going to want some high-quality wired cans.
But for portability, I think that a lot of users would dig some Bluetooth. It's already been establsihed that the average iPod user doesn't know squat about the quality loss of compressing their files and using crappy headphones.
Do you honestly think that the guy who's using the iPod earbuds while listening to his 128kbps MP3s is going to complain that his Bluetooth headphones don't sound good enough? Doubtful.
And as for size, yeah, there are still some bulky ones, but manufacturers are certainly learning how to slim them down, as you can see here:http://www.bhphotovideo.com/c/produc..._Wireless.htmlhttp://www.bhphotovideo.com/c/produc..._Wireless.htmlhttp://www.bhphotovideo.com/c/produc...eadphones.html
I certainly wouldn't call any of those bulky. Sure, most Bluetooth earbuds have some kind of ridiculous design, but a lot of the on-ears seem like they'd suit a lot of people.
Also, if you don't like a feature - Don't use it!
Personally, I wouldn't ever really use Bluetooth, but I've heard a lot of people say that they'd like the feature. If it's built in to future iPods, it's there for the people who want it. If you don't want it, just plug in your normal headphones and listen away. No harm no foul.