The problem with what you advocate is that even if they successfully use the money they did not give to Roethlisberger to acquire defensive talent via free agency and/or trade, there's a great chance they'll be no closer to winning the Super Bowl than they are now because the QB position will suck.
Too many people underestimate how QB oriented the league has become and what the implications of that are. If you have a franchise QB, you have to try to keep him and build around him for as long as he can play.
My point is not to over value the position so that it prevents the team from wining again. That is what happened with the dolphins. There are lots of teams that have over valued players and had tremendous talent at one position but were never able to put together a team of winners. Marino is a great example of an overvalued player. Barry Sanders was another with a huge salary and was the best at his spot but the team could not win. They were champions in the era before the SB and were good.
The gavens won with what was one of the worst QBs in a SB because of a great defense.
Fantasy games aside I do not want the team to overpay for a qb and then to have no defenders, or other offensive players. We have over payed for an offensive line based on what they have shown and it has hurt the team. I do not dislike Ben he still has a bit left in the tank. I think he is past his prime but still very good. His accuracy does not seem to be what it was again still good but not what it was early in his game. Yards don't mean squat points do. Consistency means a lot as well he followed up his two five hundred yard games with a loss and very low production this past season, in that instance he was not able to get us past a poor team. In the playoffs the team looked lost with out Bell.
As to getting his replacement, laundry jones does not look like it he might be the replacement for Kent Graham but not Ben. As to getting Bens replacement I would like for them to get a guy and have him on the squad so he can learn the offense and the game and be the second QB till Ben retires and then take over. Much the way Rodgers did for Farve