Hell, I love how all the TNG fans are "I can't wait to see Riker/Data/Crusher(Dr. and or son)/Worf...etc. appear on the Picard show!!!!"
And if you bring that up they're all like: "But these characters worked with Picard for years and they were a BIG part of the 24th century..."
Funny thing is: they seem to gloss over that ST: D is taking place in the HEYDAY of Pike, Spock, etc. and Pike was a well decorated and respected Captain IN this era - so sorry, it's not a stretch for Starfleet to give him command of it's most advanced Starship to investigate a threat to the Federation while his main ship (the Enterprise) is being repaired/refitted in Drydock. Also, guess WHO was serving under Pike directly in this era...Spock!
Yet, yeah, they're all: "It's so unoriginal to include big name characters of the 23rd century in ST: D..."
As for the whole: "A Fed/Klingon W#ar was never mentioned directly in TOS..."
From TOS S1 - "Court Martial" (9 to 10 years in the 'future' of ST: D):
http://www.chakoteya.net/StarTrek/15.htm
^^^
And remember the above is still not the complete list. What? Did Kirk receive the above by just walking around with a stack of books at Star Fleet Academy? I don't think so. Sounds like he saw combat somewhere...wonder when that was?