The nature of script development being, I think each Codecanyon Product should have a paid feature request tab.
The time and resources to put in improving a script is critical. I have had buyers and non buyers saying I need this feature and I can pay. Why not put it officially. We can display the feature request at the front-end in a product tab like we have support tab. The author can comment on this and quote and approve a feature request. The feature added is available in product updates.
Paid support was a good idea already.