They can! But sculpting and articulation reign supreme these days. An action feature is relegated to “baby” toys.
Not even there, anymore. At least, in so far, as the “standard action figure” is concerned.
The collector segment won’t tolerate any compromise to aesthetics or articulation. But the “kid segment” has declined to the point that Hasbro, largely, only offers the most basic of offerings. I think you can really see that with the X-Men 97 product range Hasbro delivered:
5 basic figures, one vehicle, one roleplay item, and two Titan figures (though, one of which was “cross marketed” with the Epic Hero range). While we got a solid set, several major characters were omitted- Magneto, Cable, Beast, Forge, Sinister, and Morph immediately come to mind as fairly core characters that should have made it. Pointing to another major line, Guardians of the Galaxy’s toy line omitted Gamora, Warlock and the High Evolutionary, the film’s main villain.