Name me a world in Star Trek re-boot that hasn't been destroyed or faced extinction (Nibru's world, Romulus and Remus in prime universe, Vulcan, Kronos because Praxis has already exploded, Earth because of the drill in '09, the destruction of terrorist attacks in STID, etc.). It's incredibly dark. It isn't some of the time and Kirk and Crew stopping it. It mostly affects the Federation. It's not a very bright future, despite what JJ Abrams has said. It will militarize Starfleet.
We simply don't know if that was Praxis or not in Star Trek Into Darkness
I find the Abramsverse no darker than TOS.
Even the MPAA disagrees with you. While movie ratings have become more lax, each of Abrams movies is a PG-13 rating. With the exception of Nemesis, no movie was over a PG rating.
We've seen countless destroyed ships, we've seen horrific scenes like a man's head being crushed and a Captain hit by a phaser, watching him die. These movies have been incredibly violent, and I wouldn't introduce anyone to the universe seeing all this death and destruction.