It's not because they're excessive, it's because the deaths/gram are better for smaller warheads, so you can get more Armageddon per missile with smaller warheads
https://en.m.wikipedia.org/wiki/Convention_on_Cluster_Muniti...
Signing a treaty when you would just be ignoring it is typically not a diplomatically smart move. Better to not sign the treaty if at all possible.
There's a non zero chance each year that we trigger Armageddon. Given enough years it will happen with certainty. Yet nothing is done about it. I think our first mistake in thinking about the possibilities of other intelligent civilizations in the universe is to assume we are an example of one...
We live pretending we are rational, intelligent beings but in the end we aren't very far from nature and its processes which created us.
So yes, humans are obviously part of nature. That's of course where we get our primordial emotions from. But it's misleading to say we're just like other parts of nature, when that's clearly not the case. Our problem is technological progress greatly outpaces emotional development, which may or may not even be progressing. In many ways, technological progress degrades emotional development.