Currently, workbooks are built in isolation. This means that when there are commonalities between persona requirements, developers often have to maintain multiple versions the same workbook or canvas. For example, both a management accountant and budget holder might want to see an actual vs budget canvas but only the management accountant might want to see other canvases on subledger transactions. This would result in two workbooks with an identical AvB canvas and different backing canvases.
In OBIEE, as Reports were separate artefacts, they could be added to multiple dashboards and changing the report would change all dashboards that use that report. I would like it to be possible to have a canvas saved as an artefact that can be re-used across multiple workbooks in the same way. I wouldn't expect each visualisation to be saved separately so it would work more like a dashboard page.
This would have significant savings in both development and maintenance times and ensure that parity remains across users where needed.