A lot of people are saying, "adapter for gigabit ethernet", but they do realize how un-apple like that would be right? Not to mention the additional premium you have to pay for what these people consider basic functionality (well, ok, that is very apple-ish).
I don't see why they would have to remove the ethernet port from the 15". If you're buying a 15", there's a very good likelihood that you're buying it for work reasons (unless you're one of "those" guys that likes to pay a premium for a mac gaming machine...). The slight reduction in weight/thickness does not offset the removal of ethernet in this instance. In the case of the 13", I think the argument is better for the removal of ethernet, but the 15"?
I think it's ok to minimize and remove unnecessary components, even if techies disagree with it, when your machine isn't being targeted towards professional users. When your primary audience are professional users however, it really should be functionality first...yes, even at the cost of some design/marketing nonsense.
If you're a consumer (or "prosumer", whatever that means) and you're happy with your apple products, that's fine, no one is faulting you for that. You have to look at it from the other side of the fence though, and this includes the people who do in fact use their machines primarily for work, but aren't affected by this. This isn't like the ODD issue, where trends are obviously pointing towards their "extinction", this is something that legitimately affects anyone who works on a private network at work where security and/or performance has any kind of relevance.
EDIT: Btw, the removal of ethernet doesn't affect me at all, so I'm not saying this out of some self-centered whining. I do however, know a lot of professionals who would be negatively affected by this.