I'm not sure if I know what to make of this.
On the one hand, I hate the idea of bandits, orcs, street thugs, goblins etc. continuing to beat the crap out of me when I'm the champion of Kirkwall and have fought many dangerous monsters and more powerful creatures. (#$&@ you Dragon Age 2!). So if it stalls the sense of forward momentum, I'll definately not be a fan.
If however it means that I'll be able to fight a slew of orcs where once I could fight one, and it will still be a challenging encounter, then I'm all for it.
This is my hope too. We're currently running a Pathfinder E8 campaign and that was something we noticed - Level 1-3 monsters are still going to be relevant, although the numbers or other factors may need to increase.
Which is how it should be, IMO.
On the other hand, I can see there being some sort of dividing line - say orcs are relevant to level 10, at which points orogs or the like take over.
But ideally I would prefer that there isn't that clean a division. As an example, a level 15 Fighter encounters a standard patrol of orcs (say 8). He looks at them and realizes they're no real threat to him unless they get lucky. He now has the option of diplomacy, intimidation, or calling for an initiative roll.
At level 1, he had three different options - death, slavery/being seasoned with delicious spices, or running.
At level 5-10, he figures he could maybe take a couple out before they get him, so his options are still running, death, slavery, or now he can try diplomacy.