Yes, yes, yes we need this in Advanced Roadmaps.
Imagine the situation... I have a set of teams grouped by discipline (iOS, Android, RW...etc) that are organised as to manage their sprint planning by capacity, but across those teams I have a vertical 'feature groups/workstreams' which I want to view progress on. Yes I suspect I could use filtering of component/label, but that leads to unnecessary complication or misuse. Creating a custom field which is then administrator controlled gives me the option of creating standard views across our various Portfolio of projects/programmes.
+1