I would also really like to see this feature added. If a field gets deprecated and is only used in archived programs and assets, it would be nice to have the ability to hide it without going in and removing it from every single smart list and campaign.
The lack of votes on this shows how many dirty instances there are out there hahah. I would like to revive this idea, since I really need it to keep the system user friendly. 1. When a field is archived in CRM and I want to also archive it in Marketo so that none of my users continues to use it, it's really painful to individually remove that filter from 100s of smart lists and campaigns. 2. I don't even really want to remove it from those lists and campaigns, because I want the historical data of which field was used when that campaign ran.