Zorg Empire

I normally only build cargo ships because I use them to transport resources from my other planets to one that's getting power-built.

They get destroyed indiscriminately even despite having no combat value.

Could we please get an option to let (cargo) ships live if someone's about to conduct a resource raid? Thanks.

It already exists. It is called Fleet Saving.

And the answer to your next question...

What is a Fleetsave?

Making an extra option to protect cargo ships does not sound bad imo but only for a new and newbie-friendly universe configuration.