I guess there's always at least one.
EDIT- Fine, I'll elaborate a bit.
For the record I think your argument/line of reasoning is terrible, bordering into "atrocious non-sequitur" territory.
Having an extended cast of characters rotating to fill the spots in your party in no way needs to imply that the ones you are not carrying around full time spent all their waking hours masturbating behind a rock in blissful negligence and without a care in the world.
There are plenty of ways to make use of inactive party members, both mechanically or at the bare minimum making up some fancy excuse about how they are spending their time for the sake of the mission.
Also, it seems pretty bloody obvious that any pretense of "immediate urgency" will be shelfed pretty soon, as we move past Act 1.
