But it if was all a PR stunt, why did they send them to deal with the hotspot on Nimbus III?
That much was also pretty clear in ST4: Starfleet wanted to keel-haul the mutineers, but the public wanted to beatify them. So, they get a replica starship and avoid jail, but as soon as they have had their fifteen minutes of glory, they have to face reality again: they don't get promoted and they don't get good assignments.
Starfleet went on to have Enterprises B-E
And clearly the E-D was not the replacement of the E-C - there was a significant gap in between. We are given no reason to think there wasn't a gap between B and C as well. And the ship type represented by B was not retired when C was introduced. The ship type represented by E in turn is of humbler size than that represented by D. So essentially we only get a bunch of ships with the same name but no other connecting factor.
And this is with regards to the Enterprise
, which everybody seems to agree is a venerable special case. Nothing of the sort seems to happen to the Hood
or the Yorktown
or the Intrepid
. So, a PR stunt. (Much like the one with the Defiant
, which was elemental in the early stages of the Dominion crisis and is likely to have achieved fame even outside the Starfleet circles.)