But is there really such a heavy focus on action in X3, as compared with X2 for instance?
In X2, Magneto's action is to rip the iron out of a guard, uses the iron to escape, suspends the nosediving X-jet, removes a metal wall to get into the control room where Mystique is, removes grenade pins and blows a wall up, stops Cerebro with waves of magnetic energy, realigns Cerebro's panels, wraps a chain around Stryker's neck... We also find out that Magneto knows who Wolverine is, and what his past is. As well we find out he knows everything about Charles, the limits of his powers, and how Cerebro expands them, and the layout of the mansion. We also find out that he is willing to sacrifice Charles for the better of mutantkind. Abd that he holds all mutants in high regard and try's to recruit them at every oppurtunity (I.E Exchange with Pyro). And he knows details of Strykers past and his sons powers.
In X3, Magneto stops the prison convoy and frees the prisoners, pushes cars aside on the bridge, moves the bridge, creates a metal shield to stop explosive charges, hurls cars that are ignited by Pyro. In NON-ACTION scenes, we hear him talk to Charles about the use of power, see his delight with the young Jean, learn of his international travels (implying his global terrorism activities), see his bitterness in the church scene, see him gathering an army and rallying his mutant troops, his horror at Charles' death, recruiting Jean, talking to Jean of her being a goddess who was turned into a mortal, remonstrating with Pyro over his regret over Charles' death, his shock and then the mutant supremacist coldness at the curing of Mystique, the comment of building bridges (from a comicbook storyline in which he tears apart the bridges of New York), his cold terrorism over the use of pawns in battle, his regret and powerlessness (literally) at Jean's full-on Dark Phoenix moment, his stubborn willpower in trying to regain his magnetic powers... We learn more of Magneto in X3 than we ever did in X2...
Compared with X2, we also learn more about Xavier, more about Jean and we learn a similar amount about Storm (she now needs an origin scene so badly to be a background for her responses - and we could have had more discussion in that balcony scene). We see a similar amount from Cyclops
(but with a seemingly more final and fateful outcome).
I think the movies are similar in terms of action and drama components, but X3 is more 'expansive' in showing a wider world's existence and response, and thus seems less introspective and confined than Singer's versions, replacing the internal moodiness of mutants flitting about as secret operatives with the broader passions of a conspicuous mutant world. With the war coming in X3, it suited the story to be shown on a larger scale although Bryan Singer might well have added more 'seriousness' and finesse in places.