There is value in good players on rookie contracts. That is the best way to construct a championship team. Personally, I do not want to tie up my cap space in a player like Melo because he does not make his teammates better and he does not defend well, and his position is not that hard to fill (SF's are a dime a dozen). Would I rather have a combination of AR and Gallo on their rookie scale contracts vs. Melo on a maxed out, multi year contract? If you are managing a team in the NBA, the answer should be obvious.
If your goal is to just fill the seats and go 1-2 rounds in the playoffs, maxing out Melo to go along with Amare is a viable option. If you want to win a championship, you need to stockpile talent on reasonable contracts, and either homegrow a superstar or two, and/or fleece them from another team. That's the only way to go.
The path that Portland and OKC are going is the path that I envy. We've just been so impatient that it hasn't been possible. Miraculously Donnie has gotten us under the cap in 2 years with a team that has great potential. I like the path we are on. Now, we need to get a few lucky breaks. Trading for Carmelo is not a lucky break. Getting him as a FA is also questionable since it ties up our cap while we still don't have a real answer at Center, but is probably worth the risk (though I'm not a big fan and would be just as happy to not sign him at all, I think he messes up our chemistry).
Rose is not the answer.