Yes - we can take this particular line out and write a plugin which can add it back in again. This would most likely result in most people NOT loading the plugin and not getting the discids.

Or we could just put another checkbox on Options / Tags (which is probably easier - but I would imagine more people will check this box than if it was a plugin.

I am not sure how much additional load the discid inc will actually add to the servers - it is not actually processing more entities because discid is a property of the release/media which MB is already accessing (unlike the relationship stuff which will join to recordings, works etc.) 

Or we can just drop it - I am not sure how useful having a discid tag actually is - I only did it for completeness.