There's also the question of what exactly went on during the gap between the TOS movies and TNG. Seems like there were a few hiccups here and there; the Klingon peace didn't really become a sure thing until the Enterprise C, the war with the Cardassians, whatever happened at the Tomed Inciddent (I know several novels cover these events) etc. Also the Romulans, while kind of detached from the Federation, apparently did have enough contact with the Klingons for the two to absolutely hate each other.