Defaults matter.

Very few users will ever change the default.

Some defaults are better for users and some are better for the company.

How should a default be set to be aligned with users?

Here's a sketch of a first principle platonic ideal.

Collect a representative sample of your audience into a focus group.

Give them a one-day seminar about the feature and all of the implications and indirect effects.

Allow them to ask whatever questions they want and discuss amongst themselves.

Then a week later (after they've slept on it), ask them what the default should be.

Pick whatever the majority say.

Obviously this isn't practical in most cases, but the more important the default, the closer to this ideal you should get.