There are two situations, as I see it:
A) You coop every time, all the time, no matter what
B) You find the need for strategically not cooping to gain a specific place in the rankings

For B, the only time I would find it necessary is in a situation like this:

You're red alliance, and you have a 99.99% chance of winning this match. It is your final match of the day, but there is a team on the blue alliance who is very close to you in the rankings that has 1 more match. This team has a 50-50 shot in winning their next match, and has a large chance of cooperating that match as well. If you cooperate with them this time, and they win/cooperate their next match, they will pass you in the rankings. If you don't cooperate with them, then there's a chance they won't pass you up, and you'll remain the leader.


Only time I see an advantage to not cooperating.

And to answer any questions of yours I may have missed:
1) The team should make the decision by looking at the rankings if every team on the opposing alliance, and seeing if event B can happen.
2) The drive team (and drive coach) should make that decision.