I am a huge fan of horror games, but when it comes to the question of adding guns, I'm not convinced one way or the other which is better.
On one hand, the guns seem to take away from the horror by giving a way to remove enemies, and a lot of games fall into the "I just want to kill zombies" trap.
On the other hand, games that implement guns well adds an extra layer of game play, besides just running away or avoiding enemies. It gives the player hope, something they might not have without weapons.
At some point in the distant past, the universe went through a phase of cosmic inflation, Stars formed, planets coalesced, and on at least one of them life took root and developed into the human race, who conquered fire, built societies and developed technology .
All of that so we can argue about nothing.