I actually had a similar thought earlier, but dropped it again because the people we've been following are hardly average 24th-century humans for example - they have reason (and have been seen to) reference historic events that relate to their own line of work, either as a source of inspiration or because they might be more directly affected by and aware of the consequences than average citizens. I'd expect US military and political leaders to be much more likely to reference the Spanish-American war than someone working in a bakery (then again, maybe the Spanish-American war had significant repercussions for pastry culture?).
I'm willing to allow a larger suspension of disbelief in this respect, particularly because we (in the Doylist sense) know it's because these events didn't occur until they were created. Still, I tend to assume A LOT of stuff has happened over the years in Starfleet too.
So if Peter David wanted to do the Thallonian War or Christopher wanted to do a Klingon War we'd never heard of, I'd be cool with that.