It’s also possible the B was retired early for political reasons. Perhaps at this point Starfleet wanted a new Enterprise every 20 years or so as their new flagship. It certainly beats yet another Enterprise lost or destroyed in the line of duty.
Or maybe it was always intended to have a 30 - 40 year run, followed by retirement. And politics didn't factor into it.
It’s odd for Geordi to bring up the (non) possibility of the E being used if the entire crew already knew it was destroyed.
Maybe because the Ent-E was better armed than the Ent-D, and had been proven to defeat the Borg in battle before.
And, more importantly, they were having fun with Worf.
There’s a scene at the end of the battle where both the Enterprise-D and the Titan-A fly over the wreckage of an Odyssey class starship. I took this to be a foreshadowing scene for the Titan’s renaming, and that that wrecked ship was supposed to be the Enterprise-F.
You could.
Or you realize that there were thirteen Odyssey class starships present on Frontier Day, and Spacedock likely destroyed one of the other ones instead of the Ent-F.