Yeah i know its not allowed and i have been providing free themes for ages since 2005 i believe and my count of free themes is highest by any individual here so far!
Yeah, that's quite an achievement. The problem is that, there are many scammers in this community & i know a theme designer personally who have scammed many people here. What will he do? he will create a new account, release a free theme & promote it through vb.org & will start scamming again. Since scammers are not banned here, there is nothing we can do to stop people from creating new accounts & hide their original identity.
Use your signature & footer links of your free themes to promote your service. That will be your best option IMO.