Change domain on analytic field in timesheet view

Having contract out of the "types" allowed in the domain makes it impossible to chose those while people enter their timesheets.
Without this module, the contract type is allowed there (have a look at the domain on hr.timesheet.sheet.form). Is there any reason to change it when we install this module as people can still log their time on contracts from the same view?
Also I wonder if we shouldn't ask only accounts and contract having use_timesheet == 1