Only ruins the game if you have a shit kd...
The point of the game is to kill each other.. kd proves how good you really are..
maybe have a ratio for captures? (objective like ratio)
As I said before, anyone can have a high K/D by simply playing Infected on a regular basis. I don't invest anything in K/D anyway because I'm an objective based player. When playing a mode like Drop Zone I can finish top of the board and win the game even if I only get 5 kills. When I go in to a lobby I look at the all-time leaderboards and that tells me who has played this game mode the most, and who's been scoring big. For me, that's the best indication of who's either good or bad. Although having said that, it's just stats and I'll be waiting for the game to start before seeing who's who.
You say that having a poor K/D ratio "ruins" the game but I don't understand that. I don't think the amount of fun I have with COD is dependant on my K/D ratio. But then again I don't care about K/D ratio at all. If someone gets too obsessed with those stats and begins dashboarding their games (which I know happens) then I can see why that would ruin the experience and fun for them.
If K/D means a lot to you that's fine. That's why I say keep it hidden but not to remove it. If it's hidden then you can still see it and challenge yourself to keep it high if that's what you enjoy doing. I've only been playing Ghosts for a week by the way because I just bought my next gen console. My K/D right now is 1 which means I'm breaking even for the most part so I'm fine with that. I'll be trading the game in a week from now for Advanced Warfare so like I said, those stats are something I couldn't care less about.