It is neither Naruto's nor Kakashi's responsibility to tell everyone the truth about the Uchiha, and no they didn't cover up crap. You can't cover up what you are not responsible for, and last time I checked, Naruto was an 8 yr old when the massacre happened, while Kakashi had no involvement or knowledge of it at the time.
Sasuke knows the truth. Why doesn't he expose it if it matters so much that the village knows?
Also, what is it going to do now if people find out (decades after the massacre)? Is it going to revive the clan? Do you expect all the villagers to destroy their homes and become nomads? What is it going to do?
Naruto is the Hokage, at this point it is his responsibility. The Uchiha sacrificed their sons and daughters for the village, and deserve for the truth to be revealed. Naruto knew about the massacre's truth and didn't speak on it, agreeing to not speak on it at Kakashi's request, not even caring to actually talk in public about it.
Sasuke's just as bad as Naruto for covering it up, Uchiha or not he has a responsibility to reveal the truth.
What will it do? If people knew what kind of shit was being done behind their backs, under their noses, they'll take the initiative to stop it from happening again. Better they know and try to prevent it, than be ignorant and allow it to continue. On top of that, Konoha as a village treated the Uchiha like shit, and what do you do when a business does something rude or ghastly? You report that business and let the free-market handle it. The innocent Uchiha's that died deserve the justice of their truth being revealed.