"I think T.J. should get whatever the heck he wants," the quarterback said. "He's arguably the best football player in the game right now, not just on defense, just in general.
"One of the reasons I took less money was for guys like him to get paid, and he needs to get paid. He deserves every penny that he wants and asks for. T.J. Watt is that guy that should get whatever he wants."
Roethlisberger, 39, willingly reduced his salary by $5 million when he signed a new contract in March that freed up about $15 million in cap space for the 2021 season.
Watt, who led the league with 15 sacks in 2020 to give him 49.5 sacks over his first four years, was the runner-up for NFL Defensive Player of the Year in each of the past two seasons. After attending every training camp practice but participating only in individual drills, Watt practiced with the team in full Wednesday for the first time this season.
Roethlisberger has been through four contract extensions and three restructures since he was drafted in 2004. The Steelers have traditionally guaranteed only signing bonuses in new deals, essentially guaranteeing only the first year. After that, though, the organization typically restructures deals to give players more guaranteed money and security that way, rather than incurring the costs up front.
Watt, who is in line to become the NFL's highest-paid defensive player, is likely seeking to buck the trend with more up-front guarantees.
"The problem is, when you negotiate a new contract, it's two-sided," Roethlisberger said. "When the bosses and higher-ups are in charge, there's only so much you can do.
"So we all feel bad for T.J. Everyone knows how bad he wants to be out there. He was here every single day and he didn't need to be, working, busting his butt. He should get taken care of."
With rain falling, Watt came out with the defense Wednesday as soon as the Steelers broke into the team period -- something he hasn't done since reporting to camp more than a month ago. He fist-bumped some of his defensive teammates and did other ritual greetings with others.
As coach Mike Tomlin predicted Tuesday, Watt was finally back.
"I mean, that's classic T.J. He plays the game with a lot of energy, a lot of passion if he's out on the field," Tomlin said. "He's going to be doing that for as long as he plays."
Tomlin said he's proceeding under the assumption that the lack of practice time won't affect Watt's availability for Sunday's season opener in Buffalo.
"I thought he looked good. He was engaged," Tomlin said. "He's been a full participant in walk-throughs and things of that nature. He's a smart guy. He can learn from watching others and it's evident in watching him work today.
"We're going to push forward and continue to push forward and prepare for this game. I don't have anything uniquely schedule for him."
Roethlisberger, who has been through the negotiating process multiple times with the Steelers, said he has talked with Watt throughout the process.
"There's a lot of young guys who don't understand the process because they haven't been through it," Roethlisberger said. "That's why I think I'm able to speak with T.J. a little bit and talk to him. But the feeling in the room is that we all know how great he is and what he deserves."