The reason consumers get refurbished phones is because they accept them. That's the reason for most things. Companies will give you what they can convince most people to accept.
If there is a manufacturer's defect with the phone, then the fact of the matter is that they never gave you a new, properly working phone, despite your paying for one.
If they replace it with a refurb, then you in effect paid the new price for a refurb. This benefits the seller greatly, as it doesn't have to give you the price difference. And no, you are not "giving" them a used phone, you're returning the defective new phone they gave you. It's actually a racket, but one most consumers gleefully participate in, so you get what you get. Why replace with new when most people will accept used?
There's no reason to.
If I want a refurb phone, though, I'll buy a refurb and pay the refurb price. If I want a new phone, I'll pay for a new phone and demand a new phone if the one they send me is damaged. This is not unreasonable. In fact, it's perfectly reasonable.
I like new phones. I should be able to buy one, and phones are not casino chips. I should be able to buy a new phone that is not damaged. Everyone should be able to. What it costs to the manufacturer is no more my problem than my expenses are to them, and if phone costs go up because they have to give people what they pay for, then I decide at that point if they're still worth it. I'm not accepting less because it's more cost-effective for the seller. They don't charge less because it's more cost-effective for me.
No, the carriers doesn't agree with anything I've just said. Would you expect them to? They don't have to. A small-claims judge has, though. Twice. The carrier's position is just one of two positions, and it's not necessarily correct.
The bottom line is that most carriers and manufacturers expect you to be punished for their mistakes, and if you accept it, you will be.
You don't have to accept it, although it will involve a fight. One you might very well win, but you will have to fight for it. Whether or not it's up to you is a personal choice, but please don't act like it's a waste of time when the NFL is on every Sunday, and American Idol is in its millionth season. There are far worse and less intellectual uses of one's time than learning their local court system.
Most are perfectly happy to be punished for the manufacture's mistakes, though, and human nature being what it is, will strongly resent anyone that doesn't do the same.