When Roman can turn a hostile 70 30 crowd into an overall positive crowd with skill on the mic or busting his ass in the ring then I will agree
He does that frequently with his matches, I don't think he'll ever do that on the mic because that's not his character at all. He's much more likely to be rude and trollish to hostile crowds, he seems to enjoy doing it, too. That's fine with me, IMO, that's closer to how I would behave than how Cena acts. Cena's "rise above the hate," and how he equates that to the way he's dealt with audience hostility is smarmy and off-putting to me.
In response to the OP: Reigns is a different kind of character, but he's just as much for the kids as Cena is. Roman looks like a superhero (or villain), he's like a comic book character or an action figure come to life. His move set and his taunts in the ring are things that are appealing to children, not to say they can't appeal to adults too, but it's the kind of flamboyant thing that kids will gravitate to.
As an adult I find him much more to my liking than Cena because his more serious personality is more like how most people would behave. The few people I know that act as cheerful as Cena in the face of hostility come off fake and inauthentic.
I like his promos better than Cena's. I can't get past when JC does the faux-southern preacher voice. I have no idea why he doesn't cut promos in his normal accent, but what he does is like a parody of either Black American English or Southern American English and it provokes a negative response in me when he starts mimicking a dialect that's not his own. I didn't mind it when he was doing the thugonomics gimmick, then it was a self-aware parody and made perfect sense that that character would do, now it makes him unwatchable for me.
'Taste the Rainbow' Cena has never bothered me because it's so obvious why he's doing it. He keeps the same shirt for years at a time so there's no need for a new design or template, they can just stick it on different colors. That keeps his brand recognizable while making people more likely to buy the same exact Cena shirt multiple times.
In the same vein, that's why Reigns keeps the vest. It's not at all to leech off the Shield's popularity, it's because he's the real live action figure and those vests sell for twice as much as a T-shirt. Anyone that can be appealing to children (although the company surely doesn't mind if the adults like them, too) is going to have a ton of uncreative, garish looking merch.
Even though the writers have moved Reigns away from the blatant Cena territory since WM32 he's still not been completely immune to the crude sexual humor and childish jokes that make up a good portion of wrestling humor. I don't see any reason to believe that the differences between them are going to change the show from it's PG state in even a small way.