Sure they can. It's just a manner of working it into the storyline/environment.
I'm going off the fact that there has been no new official release of FS in SO LONG that those might be worth considering. You might argue that because the "casual gamer" does not seem to be attracted to an arcade sim like FS, if you up the ante' in physics you might be able to attract the flight/combat sim community.
Newtonian physics is an interesting suggestion, I admit. Employing it be a challenge, to say the least. You want a balance where you can do all the things a real space ship can do while still making it fun. You make it fun, perhaps, by citing that although the forward thrust of your ship is powered by its engines, a "gravometric drive" [or something like that] provides the force to keep it going along whatever flight vector you point your ship in. The "grav drive" (probably best simply described as an acceleration modifier) also counteracts "G-forces." By making its effects partial to a degree, you can then have control of thrusting up, down, left and right. Pull a maneuver that's too rough and you might black/red out. OR you might even damage your ship. In short, you invent tech for the game that allows real-world physics while making it play like a game. Arcade simmers and serious simmers alike are happy (I'm both, actually...)! Also fills the story with cool sci-fi tech.
If I'd add more wants, they'd probably be this:
-New, better damage model. You might still have "hit points," but you'd also have sensitive areas and ship limits. Get too much "nasty" to one point and you'll be in trouble. Overworking the engine or the reactor in general? When it goes critical, the integrity of the ship gradually, then progressively deteriorates. This brings me to another cool universe-expanding idea:
-Ejections: Say you're in a critical hit scenario - If you want to live, you've gotta bail! In this matter we also add another element to the universe: Support ships (if they were real) would imaginably do more than just rearm fighters. Already they can switch out modular subsystems, but they might provide pilots with consumable supplies for long-endurance patrols, they might refuel the fighters (though I doubt it: I'd assume the FS fighters rely on a nuclear fuel that's VERY dense and takes a VERY long time to expend), but they'd probably also be employed in the SAR role. Think about it: they're big, pretty fast, and reasonably rugged. There's no reason to assume they wouldn't be used to ferry personnel or pick up a downed pilot. That pilot has a space suit for a reason! If nothing else, it lets the mission have a story (and adds a cool game element).
-SKINS. Not only might you have the squad patch on your fighter, but the skin for the squad might also be unique. It would also work the same for all allies/enemies. Just another way to make the universe more dynamic.
In a way, I'd love to see FS3 as a sort of "Il-2 in space." Of course, it would loose the tedious stuff, etc., etc.