Exactly, there wouldn't be as much an outcry of VOY ruining the Borg if all that's left are depowered remnants and not a single group as powerful as the TNG Borg.
The other option is that the writers could have abided by what they wrote in "The Gift" and accepted that Voyager had been flung out of Borg space and woudn't be returning to it (except, perhaps, in a story like "The Raven" where they back track to Borg space, or "Hope and Fear" where another alien tries to take them back into Borg space). In fact, such a move would have probably made shows like "The Raven" and "Hope and Fear" more effective, since the idea of "Borg space" would actually have some meaning.
Probably, but what with the "speed of plot" thing and lousy writers wanting to cash in on the Borg's popularity they'd keep bringing them back anyways. Having some other stronger species just destroy the Collective, leaving weakened remnants behind would solve the Borg problem, leave them open for re-use without anyone complaining they were emasculated since the Collective's power was gone already, and allow for more interesting stories dealing with the collapse of the Collective. For example, other DQ species might begin an extermination campaign to wipe out Borg-infested areas and draft VOY for the cause. Or Borg technology becomes a new black market item, etc.
Well, if the writers were ready and willing to ignore one premise to bring the Borg back, I doubt mostly destroying them would have changed things.
It would have made it easier for the audience to accept it, possibly. They'd think "Oh well, the Borg's power was destroyed off-screen beforehand so VOY winning against a shattered Borg remnant isn't so unbelievable". And also, the Collective being destroyed and the DQ reacting to this is a far more interesting premise than simply being teleported beyond them.
It's certainly an interesting premise. Better writers (or, less constrained writers) could have done something with it.