I'm not sure I follow you here. Are you saying they can spam Dailies each encounter if they spend a day resting between each? Given the absence of Rope Trick or easy Teleport, the feasibility of stopping for 18 hours after each fight is much less than it was for 3.5, and the limited role of Daily powers vis-a-vis 3.5 spells makes it that much less enticing.
I'm not saying that it's easier, simply that it can still happen, and that the big difference is that now all classes can do it.
What I'm taking away from this is that you don't believe there's any problem in PCs prebuffing their capacity, and therefore the entire Powers framework is irrelevant and should be scrapped in favor of mechanics that allow an Artificer to spend time out of combat to improve their capability in combat. The only question is how much they should be able to prebuff themselves. Is this a correct reading?
Yes and no. I'm saying that there's no power difference between an Artificer who uses his downtime to make the gadgets and an Artificer who uses the downtime to replenish all their powers, except that one Artificer has more choices as to what gadgets to make and how many then the other. The Artificer could technically, I grant you, just burst down ALL of his gadgets and awesome abilities all in one combat, but they he couldn't do the same in any combat afterwards until resting. The thing is, he can already do that under the Powers system - there's nothing stopping him from slamming down all his Dailies in one fight.
That's why I hate the Powers system, or at least one of the reasons. It's still Vancian casting, only now EVERYONE has it, and they've removed some options to make sure you don't "make the wrong decisions." Now mages can't use all their fireballs or whatnot in one combat and be stiffled on the next, because that would be a bad decision on their behalf. But I don't like how they aren't given that choice. That's my gripe with Artificer. The Powers system really stifles the gadgettering. Instead of the James Bond/Macguyver "Don't worry, I've totally got a tool for this somewhere," it's more "Well, sorry guys, but I chose to learn how to throw wire instead or cubes. Can't help you there."