Allow "not equals" Operation in Filters

When using the Widget Filter Editor, one can add any number of criteria to include, but there’s not currently an option to select single values to exclude.

Say I want to search for all Threat Categories for a specific organization or team except one or two. Or I want to check on emails from all Sender Locations except the US.

It would be nice to be able to only exclude the specific categories instead of selecting everything except for them.