On ArcGIS Online Item Description pages, the auto-generated Update Date is the most prominent revison date. For dataset- or service-type items, the auto-updated Update Date is not appropriate as it makes it unclear what version of a dataset is being used.
Allowing content creators to set this date manually using the metadata Revision Date (as is possible on the Open Data site) would give more control to content creators to provide confidence to users in the data they find.
At a minimum, displaying a Revision Date more prominently on the Item Description page alongside the "Item Description updated date" would provide more clarity to users that they are using the correct version of the data.