Cena spoke with Forbes' Alfred Konuwa about that topic and other matters in an exclusive interview that published Tuesday.
"I guess I've viewed the WWE as a product outside of myself for a long time. I guess that's why I was so interested in the business side of it from very early on in my career. In that, I've seen it evolve, but I've also been called 'everything that's ruined sports entertainment.' I could look at the economics of it and make an argument that between myself—and the large amount of folks that carried on the roster beyond the Attitude Era into the Ruthless Aggression Era and the Reality Era—the fans of the Attitude Era certainly looked at our product as not what they're used to, and it wasn't. So I may have a bit of disagreement with Undertaker's word choice because I don't think it's soft, I think it's different."
Cena also spoke about how "Stone Cold" Steve Austin, who has made appearances during the WWE's PG Era, had to adjust from his heyday in the Attitude Era, when he had the freedom to chug beer, curse, toss up middle fingers and do other things he couldn't get away with today.
Cena said Austin told him, "I don't know how you do this!" but also gave credit to the Rattlesnake.
"But if he had enough time, he's a great performer, he could get used to it," Cena said.
"I try, it's tough right now for me. The product has changed so much and it's kind of off. I'll probably piss a lot of people off but they need to hear it. It is what it is. To the young guys [who think] he's a bitter old guy, I'm not bitter. I did my time, I walked away when I wanted to walk away. I just think the product is a little soft. There's guys here and there that have an edge to them but there's too much pretty and not enough substance I think right now."
WWE Superstar Roman Reigns addressed those remarks when speaking with Jimmy Traina on the Sports Illustrated Media Podcast (h/t Marc Middleton of Wrestling Inc), noting how today's matches are far more physical in part because of "false finishes":
"We do the same job. It's not like the bumps got any worse or any better. You're always hearing 'a dropkick was a finish back in my time.' A dropkick is like the second move you see in a wrestling match nowadays. We're doing a lot more. And sometimes I think we're a lot more physical. And because the audience has seen so much more, we have to do a little more in order to pique their interest, in order to show them something different.
"What we call a false finish, a pin that people believe will be the final move of a match, we go through those like Steamboat-Savage. You'll see that on a SmackDown. You'll see 15 false finishes on a SmackDown."
Reigns did make it clear how much he respects 'Taker, believing he may have "misspoke."
"Because Mark [Calaway] is a really good guy," Reigns said. "He's very knowledgable. Obviously, he has a ton of respect for the business."
The Undertaker is one of professional wrestling's most decorated and respected members of the industry. The seven-time world champion and six-time tag team champion also earned a Hardcore title and a Royal Rumble win during a WWE career that spanned from 1990 to 2020, ending with his record 25th WrestleMania victory.
When he speaks about the business, people listen, and it merits a response from some of wrestling's biggest names, such as Cena and Reigns.
There may be disagreement on this front regarding whether today's business is softer or tougher than previous years, but the mutual respect between stars of yesterday and the present day is evident regardless of opinion.