Granted, there are many nice things about Confluence. But it's not only sunshine and unicorns. Here are a few of my hang-ups - some have been there for 10+ years!
- No checksums available for products: https://jira.atlassian.com/browse/CONFSERVER-25687
- No automated way to set-up the product: https://jira.atlassian.com/browse/CONFSERVER-45381
- OpenJDK is not supported: https://jira.atlassian.com/browse/CONFSERVER-16431. This forces people to use the evil Oracle JRE/JDK: https://confluence.atlassian.com/doc/supported-platforms-207488198.html
- It's not possible to rename a space key: https://jira.atlassian.com/browse/CONFSERVER-2085