Yes I agree that you want the diameter as large as possible to reduce the resistance and heat but in most cases you have to balance it out.
The wire resistance depends on its cross section area, length and material it is made of.
The weight goes up with the diameter and the length of the wire.
The current draw out of the battery goes up with the weight.
The heat goes up with the current.
Those temperatures in the table are insulation ratings, this does not mean that you will get those temperatures just after plugging it in, it depends on the initial temperature of the wire and ambient air temperature, cooling of the wire, current flowing through the wire and how long it is going to flow for.
There is always some heat generated when current flows through a conductor the questions are how much heat, over what period of time and is it safe?
I do not think there is a ready solution to this problem and I can not just tell you “use 8AWG”.
Can you please tell me where are the 20A, 80A, 100A from?
You can also look at wires in your escs and batteries and use the same AWG, not very scientific but usually works.