we all know that metadata is important but for many we are too lazy to worry about it as much as we should. My idea is a bit like the warning that pops up when you add a data set with a different coordinates sytem to your existing map but for metadata.
This is how it would work, when you are adding data you are notified about its metadata if it doesn't meet your standards. ie if the that the data is from an untrusted or unkown source you are notified, if it is out of date, if it was created at a scale that isn't suitable to your needs etc. Where the 'filter' comes in is that the user could configure a filter that forms the basis of the notification ie what date range is appropriate, who is a trusted soruce etc.
The outcome of this is that we would all start to pay more attention to metadat and improve the quality of the work we do, organisation could use this to better enforce agency wide standards and a great feedback loop would be created where we would start pushing back on data producers that they need to lift their game to ensure there data quality/standards are fit for use.