Scheduled for Sites 9.5.
The idea of user-based time stamps is definitely a familiar request and applicable to global or Cloud customers and deployments.
Current approach to implement this idea is to switch CM on server side (database, server logic, TOM.NET and CoreService APIs) to use UTC times only. Content Manager Explorer and Experience Manager will convert all date/time values to user local timezone on the fly. This change will be applied to all date/time values exposed in API, such as modification date, scheduled publish date, times when publish stansaction changed its state (e.g. from Rendering to Transporting), when workflow activity was started etc.
Implementing this will introduce a compatibility break, so there's a bit of investment to align the date format across the user, lists, Content Manager, and Content Manager Explorer. We'll have to see how much interest there is and the impact on users and the system.