Re the first part of the question. Why change from registration district?
The England standards page includes the following
Where the most precise location for an event is a Registration District (for post-1837 events), which may contain several towns and/or villages, the Registration District may be included in the location. The biography should make it clear that the location refers to the Registration District, rather than a village or town (which may have the same name). https://www.wikitree.com/wiki/Space:England_Project_Profile_Standards
This doesn't actually say don't state registration district in the location field but could be interpreted as not to do this.
Like you, I had a location edited recently. It was a marriage, changed from ' Rugby Registration district' to 'Rugby Warwickshire.' This registration district, from 1837, included parishes in Warwickshire, a couple in Leicestershire (-1895) and several in Northamptonshire (-1932). Although I don't know exactly where the couple married, the least likely alternative is a parish in Warwickshire . It's very unlikely to have taken place in the town of Rugby. I originally put 'registration district' in the location box after a question on G2G many years ago. Policy obviously seems to have changed. In this case, I've removed the marriage location entirely because I feel Rugby, Warwickshire is inaccurate and misleading.