Separate "question required" from validation settings.
Currently a question is set to required by checking "Enable Validation (require response)". But use of field validation, such as sums totaling to 100, requires that the same "Enable Validation" option be selected. However you might want a question to, e.g., total to 100 when it is answered but not require that it be answered.
The "question required" option should be separate from and independent of the validation settings.