With the current "list" architecture, no list is ever going to display information or, more importantly, allow filtering on all possible information.

So, a reasonable workaround is to allow every list to display and filter on custom fields.

This way, one can always "tag" records with a custom field value and address only those records.

e.g. we needed to graduate a subset of our seniors. we needed to click 300+ times individually!

If the system had let us filter on a custom field, I could have simply tagged the records simply [via import], then filtered on only those. I would not have had to compare lists and click manually.