The game was advertised to have PVE. It released with PVE. Bots are part of the game. If you didn't want to play a game that had PVE why did you buy it? PVP is there for you to play exclusively. Why does it bother you so much that there is an option for people to play against bots?
It's because your very existence and self-esteem hinges on having better stats in a video game than someone else, isn't it?
I got news for you. NOBODY cares about your K/D. NOBODY is taking money out of your pocket by playing against bots. Just play the game your way and let others play the game their way. As long as it doesn't involve using exploits (ie jumping, sliding, strafing around to manipulate hit boxes) or using loopholes in the game (ie xp farms) then it's not hurting anyone.