I'm not sure how it could be saved, we see Spock's memory of the destruction of Romulus. That's pretty hard to interpret any other way.
But even if Romulus were somehow saved, it's basically undoing Nero's whole character arc in Trek XI. Remember, Nero wasn't always an evil guy, he was just an honest hardworking average Joe until the destruction of his home and death of his family drove him into a murderous rage thereby resulting in him destroying key Federation worlds. What an embarrassment it would be to find out Romulus was saved and he was killing billions of people for nothing.
Hmm, that could make for a good scene.
Nero: "IT HAPPENED! I SAW IT HAPPEN! I KNOW IT HAPPENED! DON'T TELL ME IT DIDN'T HAPPEN!"
TARDIS noise is heard as TARDIS appears behind Nero. Matt Smith Doctor walks out.
Doctor: "Hello, Nero, I have news. It turns out you are wrong, the destruction of Romulus didn't in fact happen. Myself and my other incarnations flew around Romulus just before the supernova hit and shifted the planet into a pocket universe. It's safe, your people and family are all okay."
Tom Baker Curator steps out of TARDIS.
Curator: "Romulus falls No More!"
Doctor: "Exactly. So, all of this, destroying Vulcan, killing its population and the crews of those Starfleet rescue ships, torturing that poor fella there, is kind of all for nothing."
Nero stares at the Doctor, wide eyed and full of confused regret. Nero then turns to Captain Pike, strapped to the table with a Ceti eel wriggling around his ear.
Nero: "...Sorry...?"
What matters to Nero's arc is that he genuinely believes that Romulus was destroyed, and that it was Spock's fault. Whether that actually happened is in many ways irrelevant, just as Gallifrey not actually being destroyed doesn't undo the Doctor's arc prior to the anniversary special. And anyway, 99.999% of the movie audience would never even know that things happened differently in the books.
As for the *why* you might want Romulus to be saved in the novel-verse, because (1) Romulus is awesome, and (2) the Romulans are essential to maintaining the balance of power the Alpha/Beta quadrants. Throw the Star Empire into turmoil and the Typhon pact is no longer a threat, and suddenly you either have to come up with stories where the Khitomer Accord powers have essentially no competition, or you need to make up a new adversary not from local space (as the Borg are gone, and the Dominion are isolationist).