A game normally has several phases. The exchange of pieces or a change in pawn structure can be natural breaks between two phases.  Often the exchange of the queens is such a break ...

In this position White played 25. Qxe5 to force a Queen exchange. It was the break between two different phases .

                          Pressure in the d-file (before exchange)

White kept the d-file open and succeeded invading with his rook

Excellent piece play instead of pawn grabbing (after exchange)

In the endgame  after the exchange of the queens Botvinnik demonstrated masterful understanding and excellent piece play. Instead of grabbing some pawns on queen side he improved  consequently his pieces. At the end everything worked well together and the win was like picking a ripe fruit in autumn

Finally we can say that Botvinnik reached a promising position after pressuring in the d-file. Then he exchanged the queens foreseeing that he would get the better endgame. This is the way how real masters play chess! :-)