It can be fun no doubt but I rarely get competent teammates. I have a decent SPM in domination but what ends up happening is that I am just about the only one who tries to capture point "B" so I end up dying non stop. I will end going like 13-25 because of it, Meanwhile I will have 3 people on my team that go 45-10 with no defends or captures in a losing effort. The issue is that people just care about upping their KDR so they go around killing people instead of capturing points. That is why I mostly stick with TDM.
I guarantee people would start trying for objectives if:
A) When playing a non death match game (Dominations, Kill confirmed, hardpoint, CTF) all it shows is the revelent stats for that game: IE captures, defends, caps etc.
B) Your overall KDR is ONLY made up of games where the object is to kill people (TDM and FFA) That way if someone just wants to kill people in domination great; it will not improve your overall KDR.
I agree with you on some points, disagree on other points. I should start by saying I only play Objective modes.
First a person's KDR is relevant when playing Objective modes. It directly effects the other team's ability to get a scorestreak. Example: If someone is going 3-30 they have died 30 times given the other team at least a total of 3,000 points (potentially a lot more if they are objective related kills) while only ending a scorestreak 3 times. I tend to notice that when I get 3-4 Lodestars in one match, the other team has several people who are going 2-20, 5-31, etc.
If your team is giving the other team scorestreaks, it has a HUGE effect on Objective gameplay. 1 Lodestar can change the entire outcome of a match of Domination, for example.
Second your KDR is relevant if you play certain roles. I have friends who whenever we play Domination, all he does is pretty much flank the other side and continuously mess with them by fake caping their points then killing them they are distracted and run back to that point. He will pretty much never capture points or hold down hardpoints, but does A LOT to help us win by simply really screwing with their ability to co-ordinate anything.
But generally I agree that people's obsession with KDR leads to having HORRIBLE teammates. Your suggestion in (B) is not a good one IMO though because people need an incentive to keep themselves from rushing the point like idiots with no fear of dying, hoping to eventually complete an objective. While KDR isn't important in objective modes, you should be completing the objectives by using solid strategy and planning that minimizes your deaths. Even when I am 100% objective oriented I still rarely if ever go negative. Remove the death penalty and idiots will just play stupid in objectives to boost their SPM and level fast.
My best advice on playing objective modes is to either join a clan or play with friends. I play with friends who are in my clan often. Makes it a lot less frustrating.