... I understand this. But have you ever seen more then 5 written request for a specific feature? Suggestions are not polls. With suggestions, 1-5 people write about it, the rest of the users read and agree silently.
It would be unfair that non-vbulletin users are getting punished because there are more features available only if you use vbulletin (there are some forum software out there, which are significant better than vbulletin).
If someone wants to make money with his internetsite (we all do I guess), this usergroup differentiation is one of the more obvious and easy possibilities to cover the costs of running a site.
You need costumers that buy classifieds. If you make it easier for them to cover the costs by features like this, you will more likely sell more licences...