I agree with you that it probably does depend a bit on the type of forum you run. Your forum seems centered around offering paid services of some sort. Trying to get sales and trying to get people to freely register for and participate in your community are likely a bit different. I think good design is still an important aspect even for an e-commerce website, but, maybe it's not as important of an aspect. What really matters is the quality of the product your selling.

In my case, the content plays the biggest role, but I agree that good design could also help. I'm still trying to find someone who will improve the look the website.