I'm pretty sure that the nostalgia effect is responsible for most of this, and natural evolution of what defines "badass" exactly is responsible for the rest. For example, it's seeming more frequent that the silent and cunning (eg Gordon Freeman, Link, Chell from Portal, etc. Even some antagonists show this trait) types are becoming the loved heros rather than the boastful powerful ones (eg Odysseus, Duke Nukem, etc).
These actors, have imho, played some of the finest Badass roles in cinema.
Claude Van Damme. Badass with a sense of humor.
Steven Segal. Badass gone to seed.
Bruce Willis. Frustrated badguy: "What does it take to make you scream?"
Bruce: "Play me some rap music..." - The Last Boy Scout
Bruce Campbell. Badass with a chainsaw, shot gun and a sense of humor.
Charles Bronson. Badass. Special award for tackling some of the weirdest ethnic roles with guts and style.
Clint Eastwood. Badass Preacher, Badass Cop, Badass Outlaw.
Jackie Chan. Bruce Lee may have had the Martial Arts, but Jackie got the Sense of Humor as well!
And a special award for Sigorney Weaver. Whoever she plays on the screen, the grit your teeth and smile determination shines through.
Saxton Hale is still badass.
But we indeed need a lot more badasses. People who don't run around rainbows shouting stuff about "love" and "friendship" and "working together". People who make funny remarks when they see a nuke coming right at them.