There are many reasons that I think we all enjoy our favorite Cimmerian and they are as follows:
A.) He's a man's man. In today's American society it almost seems cool to be metrosexual, go to the tanning bed, and shave your chest. Don't even get me started on the emasculation of the American male in today's society. Gone are John Wayne, Clint Eastwood, Sylvester Stallone, and Arnold ENTER Brad Pitt, Tom Cruise, and the era of the pretty boy.
I don't know about you, but I don't read Conan stories specifically because he's a big strapping guy with loads of hair on his chest. I also don't make it a habit to insult others just because their body types don't fit my ideal. What this poster is attempting to say is exactly what Chuck Palanhiuk said 100 times better in Fight Club. Brad Pitt was awesome in that by the way, So was Edward Norton come to think of it. Neither of them would fit this posters narrow definition of masculinity, but I sure as hell wouldn't want to run into Tyler Durden (Or Mickey the Pikey for that matter) in a dark ally. If you know anything about Palahniuk, you also know that being a small man dosen't make you weak or emasculated, and simply being a big strong man dosen't protect you. That criteria lead partially to the death of his father.
I'm sure a lot of women find Conan to be attractive, but just as many swoon over Daniel Radcliffe, Orlando Bloom, Robert Pattison, and your much derided Tom Cruise and Brad Pitt. It's a big world and theres room enough for all manner of body types. You and others like you seem mainly bitter at getting old. Your favorite actors aren't particularly important anymore, or are now directors rather than stars. It dosen't change a thing about them.
It's also unfair to compare people to John Wayne. No one else can be like John Wayne. The fact he was allegedly based on a hodgepodge of character traits culled from the stories of an aged Wyatt Earp (which is unfathomably cool if true) not withstanding, John Wayne was a character that Marrion Morrison made up. That dosen't change the fact he was a cool character, but don't mistake that for acting ability. He had one character and all other characters were written to be played by him. He was already divorced from the real man by 1. When some one attempts to act like him, they come across as a caricature. The same is the case with Stallone, Swarzegnegger, and even tom cruise and Brad Pitt. Just look at Saturday Night Live's Celebrity Jeopardy if you don't believe me. These celebrities you mention are every bit as fictitious as Conan himself.
I have a Y chromosome. I had to sign the Selective Service card. I am a Man. But since I only weigh 140 and am only 5'8". Which by your seemingly arbitrary list body and attitude types of what constitutes a "Man" I wouldn't count. Not every male on the planet fits these criteria of manliness that seem mandated by so many.
Many of those doing the mandating, if the photos from Howard Days are anything to go by, shouldn't be casting aspersions either. Spears and Grass Houses and all that. I'm not trying to be insulting, many people have valid reasons, no, uncontrollable reasons, for being like they are. Malnutrition, over nutrition, poor nutrition, genetics, childhood illness, the list goes on and on. As the recent film Captain America pointed out, it dosen't matter whats on the outside, but whats on the inside that counts.
One last fun fact, the "Average height" around the globe is between 5'2" and 5'5". Which last time I checked, Audie Murphy (who also had a "pretty boy" face), was right on the line for. I'd like to see you argue that he wasn't a Real Man(tm) because of it.