The topic title implies that there are only two options. There clearly are more than that though, as is demonstrated by the differing definitions as to what those words mean. It's a false dilemma, which is why I originally posted N/A.
Going by the official definitions, status quo means things are what they are. They are preset in advance, and while they are not static, they are predefined. The alternative is that enemies are specifically designed around the party. But think about what that means for a moment.
If the Fighter increases his AC by 2, suddenly all enemies get +2 to hit from somewhere. He should have saved his money.
If the Wizard gets a Wand of Invisibility, more opponents will be creatures with natural scent/blindsense/etc than if he did not. Again, he shouldn't have bothered.
As you can probably imagine, the effect of the alternative is that your actions and decisions do not matter, because they will be entirely nullified. Instead you should run around naked while shouting your own name as loudly as possible. Then 90% of your opponents will magically vanish and the remainder will forget 90% of their combat ability! Just like the Elder Scrolls series.
With status quo however the enemies are predefined. They are what they are. And what they are is creatures in a very dangerous world in which magic is the greatest threat they will possibly face and mundane attacks are easy to nullify. Given that, you aren't going to have very many enemies easily shut down by magic. It doesn't matter that you aren't specifically nullifying a specific caster because high saves, touch AC, immunities etc are simply logical things for them to have if they can get them.
They are not static however. If some enemies become aware of the party, they are likely to start taking more specific countermeasures. As is though they are what they are. There are no solutions built in, but there are solutions that can be found. What that means is that good players/characters/plans get rewarded and bad ones get punished.
You can probably already imagine which I go with but in case you haven't gotten it yet here is the most recent example:
I had the first encounter in my campaign entirely designed before I knew anything about the party other than the starting level and party size I wanted. I didn't even know who would be playing through it yet.
By the time the first encounter was done, I had the first 15% of the campaign designed.
By now, I have the first 35% done.
Knowing that their actions are what delivers or damns them is motivating my players to play intelligently and to regard dangerous situations as dangerous.