In a lot of ways the reviewers at these sites are similar to call centre workers. They're expected to maintain quotas.

When you're trying to get through a large backlog reviews, that doesn't leave much room for tailoring responses to people.

I'm not justifying it. The process leaves a lot to be desired...I've seen quite a few things rejected that I would be happy purchasing.

Regarding improving your own work, perhaps you could ask someone else to review the theme before you submit it.