I disagree. Combat mission is the only mode I play because it's the most enjoyable. Sure, sometimes it depends the team you get thrown into which accounts for the first 2 scenarios you mentioned. However, those first two scenarios aren't very common. I have rarely, if ever experienced your third scenario. And the 4th scenario, pretty much never. What I experience most, in all honesty, is random outcomes. There have been times where I played for a few hours straight on the same team with the same players against the same team and players and it was impossible to predict which side would win.
And what you mentioned at the end of your first post, you can't blame your results on the team. It's not that hard to get kills/points if others on your team aren't "helping" you. It's hard to get kill streaks and point streaks though. That's why I prefer sniping. Some people hate snipers, but they never have any complaints when I have like 40 kills to 5 deaths and drop support actions on the objectives they are trying to take over. There are right times to be a sniper and right times to be spec ops/rifleman.