Substantially different ages of devices (according to you, yours has been in use two-and-a-half times as long), plus manager discretion, and different venues of communication. I'd venture a guess your friend didn't march right up to the first Apple employee and say "I really need you to swap this two month old watch out because I've heard you can do that." It's much easier to start out slowly with an employee in the store (at the local Apple Store tonight, I spent more than ten minutes with an employee chatting about the new band colors. He opened up a walnut sport band so I could see it (he was curious too), we both agreed it was bandaid-colored (apropos of this thread, he talked about how he was glad he'd skipped the initial launch, because now he was going to get the Space Black watch with the black sport band, and we agreed they should have offered that as an option from the start). He also opened one of the demo stations and encouraged me to try a couple of the demo bands on my own SGS (quite a change from the policies of the initial try-ons). I ended up leaving with a midnight blue sports band (that I didn't need, but really liked), in addition to the replacement power adapter for my MBP I had gone in to get.
When you start an online chat with customer service, there's much more of an impetus to get to the point - you're doing a cold open, no chance to establish rapport, and they know you're there because you want something. It's a very different environment. Your friend went into the best environment to interact with the employees, and likely with just a hope (and got lucky), you went into a much more difficult environment for interacting with the employees, likely with an expectation of getting what you wanted, and got increasingly annoyed when you weren't given the same lucky break. I expect the Apple representative was quite frustrated with your attitude (you say you were polite, but you also let on that you asked the same thing many times, after being told it wasn't going to happen).
If you tell your friend to buy a lottery ticket, and he does, and he wins, you can certainly feel butthurt that he won and you didn't, but that doesn't translate in any way to you being entitled to win. That's why you're not getting much sympathy in this thread.
Just finished reading the last few responses. Dude. If you tell your story of woe to twenty people, and twenty people tell you that you were wrong, consider, just for a moment, the possibility that maybe, just maybe, you actually were wrong. Consider that maybe it isn't just a matter of people not understanding your plight.