It's less of an "Open Playground" and more a "Series of Interlinked Puzzles". Most of the puzzles can be solved via Raid Starship (i.e. bust open all the guard posts to get the locals pissed, kill them as they trickle into your systems, then send in a mop up force). Sometimes though, you have little kinks - Spire Shield guard post + AI Eye, Raid Engine next door, Counterattack posts, Fortresses/SuperForts. And then there's the global puzzle of "how do I keep AI progress down", which can be solved by a number of mechanics.
As for armor, I also pretty much ignore it when making tactical considerations. Usually, the AI forces are too well-mixed and not well-enough armored to justify taking the time to separate anti-armor ships from my forces.
But, you know what, it's a hell of a lot better than that "shields" mechanic that was floating around way back when. It was "hilarious" when none of my ships or turrets could shoot at the MKIV enemy ships that would show up, because their "shields" reduced my forces' effective targeting range to 0. At least now, my guys can pretend to shoot at the AI ships.
Edit: Hey, anyone remember those horrible "wave multipliers"? Like the Ion Cannon, the Zenith Power Generator and the Golems had? Man, good thing those are gone, 'cause otherwise, I'd never even consider keeping an Ion Cannon alive or capturing a planet with a golem on it.
Focus: There's a lot more variety now than there was in 3.0. That means there are more things to get in the way of how a given player wants to play (again, e.g.: Eyes, Spire Shield Guard Posts, Raid Engines / Alarm Posts/ Counterattack Posts, Core Shield Generators). Sorry the AI isn't just letting you fellas steam roll.
Full Disclosure: I've yet to win a game.