I can see both sides to this, and do share some of @Geek’s concerns.
Over the last couple of years we have been getting quite a few emails from organisations or companies asking for us to remove their links, here is a typical email:
Hello,
We are reaching out to in hopes that you can lend us a hand for a couple of minutes. Recently our search engine rankings plummeted with Google and other search engines. After investigation into our backlinks it became clear that a previous SEO company had employed less than legitimate link building technique. As a result we are now trying to remove any and all links that Google may deem as unnatural. In doing so we may remove links that are natural, but it’s part of the process of trying to appease them and recover our rankings.
The following pages on your website have links to our site office---furniture---online.co.uk:
http://site.com/showthread.php?t=40678
We would really appreciate it if you could take a couple of minutes and remove links from your website site.com.
If you need any clarification or help in removing links please feel free to follow-up.
Thank you!
On investigating these links, they were posted in appropriate threads by genuine, and longstanding members who I reckon would have easily got trust level 3.
Although I have not asked the users, it makes me wonder - what if they got paid to mention these companies or post these links? And if so, is removing nofollow on DC forums going to start encouraging similar?
Having said that, on the flip-side, it may encourage users to stick around - because they’ll know they are genuinely rewarding companies they like…