The Last Action Heroes by Nick de Semlyen, editor of Empire magazine, goes into the 'why' of the 80's action movie stars. Great book, well worth a summer read.
TL;DR: Unique factors of the stars themselves mostly growing up in poverty, the Cold War, and the film industry coming out of 'funks' in the 70s lead to this hyper-masculine juiced to the gils ur-hero of relatively 'cheap' films. Stalone really isn't like the others but was kinda forced into it by all the money he was making (guy's more of a tender-soul/starving artist in reality). Schwarzenegger is his own beast, as many will attest to. Segal is just woah ... looney tunes. Norris is also a strange duck that was super comfortable doing TV movies for some reason. ETC.
TL;DR: Unique factors of the stars themselves mostly growing up in poverty, the Cold War, and the film industry coming out of 'funks' in the 70s lead to this hyper-masculine juiced to the gils ur-hero of relatively 'cheap' films. Stalone really isn't like the others but was kinda forced into it by all the money he was making (guy's more of a tender-soul/starving artist in reality). Schwarzenegger is his own beast, as many will attest to. Segal is just woah ... looney tunes. Norris is also a strange duck that was super comfortable doing TV movies for some reason. ETC.
Again, great book, well worth the read!