Killing low level players who don't yield honor, players with res sickness, players with honorless debuff, taking them down with said effects causes your:
Rating to go down slightly depending on what it is
You lose 125 (or more depending on how much you have) CP when you kill someone in that state.
You lose a lot of honor depending on how much you have
You think gankers or random dummies would take a chance if it was like this?
Well, Dishonorable Kills did exist back in vanilla, but for some reason Blizzard decided to remove them. I'd love to have them back, but it just won't happen. On your question - outdoor PvP would be dead. People will start camping Thrallmar/Honor Hold with 60lvl twinks and Warsong Hold/Valiance Keep with 70lvl twinks or even straight 80s. Apart from that, there would simply be no other form of outdoor PvP. When several people group up against a single player of the same level, he won't be able to call a higher lvl player and the only thing he will be able to do is log out.
I'd rather see them make killing low level players give honor, it would motive a lot of players from capital cities to come and join world pvp instead of sitting afk. Would make the realms seem more populated and imo would be healthy for the community.
You think gankers or random dummies would take a chance if it was like this?
I definately would, I don't need honor, I could not care less. Then I would start camping low lvlers so hard untill someone opens another thread asking to make them unflagged untill they hit 80 with 6k+ gs. Such whinners these days I don't get it