Having any kind of game or software involves iterating through all sorts of bugs that players and users might discover. The per-product forum system is great but sometimes when debugging an issue the user might have to provide things like crash logs and other info to help diagnose an issue with a game or product. I feel that at some point that might serve to be a very huge privacy or security issue for the end user. I use itch as the primary distributor of my tools and feel it would be useful if itch had some form of ticket/issue system for users to interface with should they encounter a bug or issue with the software. Games are just software after all and inherently will have bugs and I feel itch.io would benefit from having a more facilitated way to manage them.
A whole "issues/ticket" system might be too niche of a feature to have but maybe even just having some more visibility customizations on product communities for things, or a feature that allows people that have bought or downloaded have their own sections to discuss in and ways to start private conversations with the author(s). That way the feature is generic enough to capture the "issue system" within its domain by simply adding visibility settings kind of like how kickstarter has a "backers only" section for product pages. A user could just make a thread in some special community section and mark it so that it is seen by moderators only, or just a "message the devs" feature would be enough to start private conversations with a product's "team" and could be generic enough to capture both an issue system and a generic way for a "backer" to speak to the author.