What exactly does “effective international cooperation” mean? How would you obtain that? For it, you need trust between the signatories. Trust means that there are effective inspections, and that there is time to react to violations of the treaty. That is an issue, and one cannot dismiss it without further arguments.
Moreover, why is it misguided that countries want to reduce risk for their soldiers? If you are heading a military organization, shouldn’t it be your moral obligation to reduce the potential harm that your soldiers are exposed to?
This has to be balanced with other ethical considerations, of course. There are questions of collateral damage and harm to civilians.
With autonomous weapons, a major question is oversight. Do we want to allow a machine to make a kill decision?
Funnily enough, bombs and missiles are accepted weapons now, even though they are much more indiscriminate, and even though, there is little oversight once they have been fired.
You are quite right with your concern about potential changes in the decision making of countries as this technology becomes available. Reducing the risks for soldiers can make it easier to decide to go to war.
I am concerned with the use of autonomous weapons by autocratic states. They have a lower threshold for starting a war anyway (according to some political theories), and there is little oversight, transparency and accountability, which would amplify any issue.