These numbers may be wrong in your organization so adjust them as needed.

Every feature has a maintenance cost of about 20% of the initial cost per year. If you have a team that is 100% tasked with maintaining and adding features they will halve productivity (features) in 5 years. So there is the cost of adding the feature plus the cost of maintaining the feature and then the opportunity cost of not being able to add new features.

So how much does it cost to add that feature vs the value? There may be more value in going through the code and removing these low value features than adding them but you will have to weigh that on a project by project basis.