At 30 years old you aren't going to heal as fast as you did when you were 23. Ben is still tough as nails and able to play through virtually any pain a defense can inflict. He can make plays on the run, evade pressure, and march you down for a game winning score at any time. That's a big reason why he's one of the best signal callers in the game. That being said, sometimes change is a good thing.
Perhaps Ben needs to be reigned in a bit now. He won't necessarily like but it doesn't have to be bad. Design the offense with a mindset of more intermediate passing, using the TE's and RB's, and of course still go deep here and there. We saw flashes of it against the Patriots, or for a quarter here and there during the season. You don't have to always get 50 yds at a chunk, 10-12 yds. is ok too. Roethlisberger has said countless times, I can't change who I am, that's how I play the game. He even makes light of it from time to time on various talk shows and interviews. It's hard to argue with his success, but like every top flight athlete you evolve over time and experience. Just because you can take the big hits and run away from pressure doesn't mean you should still be hanging onto the ball forever now. It's good to know that you have in your arsenal should you need it, don't get me wrong.
Think about the weapons available on offense, and how they can be used in more than just the traditional way. You don't always have to pound the ball with a good runnning back; use him in the short passing game too. You have speed at WR but hitting them 15 yds. down field and letting them take off for a big gainer still moves the chains. Emmanuel Sanders, Antonio Brown, and Heath Miller can be lethal on a 10 yd route when you hit them in stride. That's just the tip of iceberg of the ways you can use this offense and Ben's skill set to be effective. Ben may not want to change but his own sake, and the rest of his future, you almost have to right now. The window is there to win and win for years, but it won't last forever. As much as the fans can't stand Tom Brady, he and guys like Aaron Rodgers or Drew Brees get rid of the ball quickly. They aren't beat up by the end of the year and they are all near the top of the league in scoring. Ben can be that guy too, he really can. Nobody is saying he should take a back seat to those top 3 or be just like them, but Roethlisberger can prolong his career and his overall health after football if does start to do some of these things.
Part of that change involves fixing the offensive line, we all know that. If there's quality blockers up front then it opens up a world of potential success all over the field. Whoever comes in, whether is Fichtner, Caldwell, Clements, or anyone else they'll have their own tweak on the offense. Ben will need to be able to adjust. In the end, it could turn out to be a very good thing.