In older versions of SharePoint you could add trusted locations for excel services - allowing the excel files with links to external data to update in the background without presenting warnings to users.

Bring back this feature or make it so that the site it's self is a trusted location automatically, so if I have a list and I pull data from that list into an excel file which is also on the site site and then display a chart also on the same site - I can have this auto updating without giving users warnings about external data.