How to configure the default visibility to "Only the listed pages" when adding a block? When adding a block to the site: 

Home » Administration » Structure » Blocks


the default setting for visibility is set to "All pages except those listed." is there a way to set the default setting to "Only the listed pages"?

I'd guess that this possible w/ a custom module but I'd rather avoid that.
Nope. The block add admin form is hard-coded to use BLOCK_VISIBILITY_NOTLISTED (i.e. "All pages.." option) as the default option; there's no configuration setting there. The only way around this is to form alter it with a module.