Mr. Laser Beam wrote:
^ That too. But with war with the Klingons looming, Starfleet will need all the power it can get its hands on. Assuming the blueprints for the Vengeance-class ships still exist, Starfleet would be foolish not to use them.
I am not sure why there would necessarily be a full blown war with the Klingons. It seems only Admiral Marcus wanted one or was so paranoid it would happen that he resorted to building the Vengeance and using Khan.
The Federation are very active in diplomatic channels - having gunships like the Vengeance hanging around outside the klingon border will undermine any peaceful credentials.
The Enterprise is a much better representation of who the Federation are and is capable of defending itself without resembling something that is looking for trouble.