Inactivity due to it being on the internet
Members leaving that you really liked
Duplicate threads
I personally hate how threads can become dormant and I have no idea
Other members have posted on a dormant thread and it being one of the rare locked threads
1) CAPTCHAs - designed to baffle humans but allow bots to sail through.
2) Forums where a new member is told to 'use search', 'start their own thread' or 'post in a different forum'. More a complaint about behavior rather than forums per se.
3) Forum search engines, a failure on every level. I use Google to search all forums including my own. In addition, why can I not search for images by member, by forum or by date?
4) Myspace disco-ball themes with flashing user names, rotating in neon
5) My personal favorite; taking time to type out a properly thought out reply to a contentious thread only to find the thread locked when I hit post
1. The search engine came with a definable spider. SEO could work better on forums if a forum had its own algorithm to present to Google. Something the admin could customize.
2. Too many features. Sometimes there are so many features on a forum that it is overwhelming. Why have sister nodes?
3. Default themes need better customization features so that people could alternatively use them but make them a bit better looking than out of the box.
4. Page system - I think all forum platforms should offer a system that allows you to create a page for the forum. A static page that is.
5. I'd love to see a 'this addon is updated for your version' like how WordPress does it.
1. Some require to be approved by an admin.
2. Not all forums have recent activity
3. People some times think that one or two word responses are fine.
4. Duplicate threads/topics
5. Forums can sometimes have clever ideas but admins are quick to take them down if they don't take off fast enough.