[jungturk]

To the extent that these changes actually improve the non-functional quality attributes of the system, those gains can be converted into business or customer utility.

Improved maintainability => lower innovation costs, and those savings can turn into profits and/or happier customers.

Improved security => reduced risk of exploit, and that improved posture can be turned into profits and/or happier customers.

I acknowledged that not all changes of the sort you list do yield actual improvement in the quality attributes.