When marking an item as recurring payee and account should remain editable just like any other transaction. Disabling these fields adds no value but makes management more difficult.
For example, some recurring items are more generic and may have multiple accounts for a single recurring item. I want to be able to see the account that I select in the list view instead of having it be overridden by the recurring value.
At minimum, if some people find disabling recurring fields useful, there should be a preference to not do this for people who don't want this constraint.