I do think rating apps or install numbers would be great to better sort apps according to their usefulness. Number of installs/delivered updates are off the table because of how against telemetry the community is.

Ratings aren't necessarily useful since almost all apps on F-Droid are quite good at the thing they set out to do. The question is whether it's what I searched for. The biggest problem are outdated apps, which is pretty natural since life happens.

Comments are difficult because of spam and other unwanted content being posted. The F-Droid community are all volunteers and they have already enough to do.