The current structure of user security was completely redesigned under 2019 R2 to correct for inherent design issues with the previous structure.
While the current structure is much more simple in nature, the complexity of the security requirements in Acumatica make this security structure highly difficult for the typical system administration to maintain. The number of screens and potential number of user roles make for an extremely large number of possible combinations.
The current, simple structure has the follow issues (among others):
I see that Acumatica has added new default user roles. However, many medium to larger organizations have more complex security requirements and need broader control.
A hierarchical structure with inheritance, similar to Microsoft's Active Directory structure, would allow many permissions to be set at the top of a group of objects such as Payables, Receivables, Banking, Deferred Revenue, Bills of Materials, Equipment and all screens under that section would automatically assign the inherited permissions. Individual object permissions could be overridden to set individual security permissions.