I understood the comment to be about ancient screens and more user friendly UI.
I speculate that SM36WIZ not being capable of changing the step user is that it's functional intention was a more user friendly way for non-admins to schedule jobs in the system without the ability to change the step user.
But that the job can be made periodic then contradicts this assumption so should not be there either and can be controlled via S_BTCH_ADM = 'P' ( SAP Note 1716340).
I also agree that the step user should be there because that can since the beginning of time be controlled via S_BTCH_NAM.
What IMO is also missing if it is meant to be an end user transaction is that the end user can select the program here. That is functionally equivalent to SA38 authorization to attempt to run any report. Correct would be to offer a transaction which checks AUTHORITY_CHECK_TCODE and is limited to report type transactions and parameter transactions for reports, such that the job then runs with the report behind the authorized transaction and cannot be changed to arbitrarily run anything.
Worth mentioning to SAP as an improvement opportunity as well.
Cheers,
Julius