If you want to be the top billing in the company as you say, then you're going to have to cut mean promos at some point (like Jericho), or at least have a manager that can do something for you (like Undertaker). Jericho's silent schtick worked for him because of who he is. He was a household name and a recognizable guy. No new superstar (like Reigns is) would have been able to pull that off. And like I said, Undertaker has never had the best mic skills (IMO) but he's been able to get away with that by having built a formidable legacy and build a character that everyone's into. Notice how everyone listens when Taker cuts a promo these days.
In terms of quiet charisma and intensity - it's not so much the arm crossing (where did that idea come from?!) or even the primal scream (though that adds in a contrasting way to his usual stoic demeanour). It's more his presence, and his demeanour - the definition of charisma is that innate compelling attractiveness - compelling being the key word - and of course you don't need mic skills or even need to say a word to be charismatic (see Y2J's 2011 return silent schtick). It's everything from how he walks alone down the crowd, how he shrugs his shoulders, how he's stoic yet not nonchalant or distracted - it's a vibe he emanates, one that a Batista or Lashley should have had. It's like when Brock Lesnar walks into the ring nowadays - slowly, methodically, but with a chilled out almost dismissive look on his face - telling the person in the ring "I'm about to obliterate you and it will be easy and insignificant to me". I could probably elaborate more though this will turn into an acting-related essay then.
That's what I mean by "quiet charisma and intensity". As for in-ring; Brock had an amateur background so I'm not comparing but he definitely has a destroyer moveset, and is explosive; he pulls off those moves well using the combination of power and agility and to be perfectly honest his lariats and clotheslines during Elimination Chamber looked more impactful than Ryback's meat hooks.
Again, I don't get the same feeling when I see him walking to the ring. When I see The Shield coming out through the crowd, Reigns doesn't stick out from the other two for me. When they're in the ring cutting a promo, Reigns doesn't stand out from the other two for me.
It's rather indescribable what I see in him - it's like when Jim Ross blogs about a developmental talent and says "he has IT - I can't describe it but him merely walking to the ring is compelling". I don't see that in Ryback, I just see a musclebound guy walking to a ring. But each to their own I suppose; there are people who agree and people who don't but we shall see in the next 1-2 years where Reigns is.