I’d claim that there’s so much familiarity and energy directed towards the development and marketing of these actors that it’s probably tough to establish the next generation.
You're also seeing the effects of plastic surgery and/or aggressive anti-aging procedures. Actors are aging slower, superficially, and this is leaving less leading or main roles (in an already diminished blockbuster schedule) open to a new younger group of actors. The same actors are staying around longer. For marketing reasons, there is less incentive to debut a new actor (unless it's a serious prestige picture), and the actors get caught in a weird state of body modification and refusing to age. A lot of their faces move oddly now. This goes for male and female actors.
I saw Tom Cruise at the Silverstone racetrack with Mercedes during the British Grand Prix. Seeing him without makeup was a huge change from how he looked in the latest Top Gun movie. He actually looked his age.
I think Nicole Kidman has flat out broken her face with all of the plastic surgery she has gotten in the last couple years. She might look more attractive by strange Hollywood/LA standards, but she has seriously limited her own ability to emote with her face. She looks like she's practically wearing a mask now.
Very much so, advancements in cosmetic surgery as well as the strict training and supplements that were not available for older generations of actors. Take someone like Kumail Nanjiani who very clearly were on HGH for his role in The Eternals
The effect of steroids, and ultra aggressive cutters, on male actors is pretty outrageous. It's more outrageous, though, that a lot of the male actors refuse to admit it and in turn will try to sell or advertise their workouts. I think Nanjiani was kind of the nail in the coffin to the idea that actors were natty, though. His body recomp, in the time frame, was truly comical.
Tom Cruise obviously works very hard at staying in shape and training for the stunts. It's not like he just shows up and says his lines like most actors.
I would say Tom Cruise is probably the biggest male movie star for exactly what you say. His performances have a degree of authenticity to them that is unique. When you see the stunts, you're often seeing him, and this gives his films a unique thrill and feel.
That said, Top Gun had some pretty incredible makeup and/or CGI for his face. The lighting in that movie was also phenomenal. The result was an almost uncanny valley look to him where he looked simultaneously old and young all at once. I was especially thrown off by the pre-movie screener he produced that thanked the audience for seeing the film in theatres. He looked a solid 5-10 years older in that screener compared to Top Gun, which was filmed mostly in 2019.
Yes, he definitely doesn't follow the convention approach like other leading actors. You might even call him a "maverick" for having a strong independent opinion on how to make and showcase movies.