I think there are a few points worth discussion here, and they are getting mixed together...

1. I absolutely respect someone's right to restrict the use of an item they give away for free. It's theirs, go ahead and restrict it any way they want.

2. Like many others here I simply never install anything that isn't CLEARLY marked as OK for commercial use. I don't have the time keep track when I am working on a project and I don't want to be wrong. To be honest, that's not a problem because often the free stuff isn't suitable.

3. This is in fact the same reason why I make sure my clients don't rely on GPL licensed software, the restrictions simply make it too dangerous to keep around in a commercial environment.

4. I don't think it is wrong to simply wish for a checkmark or an indication so we don't go wasting our time on the download. Seems like a win-win. They don't want me to use it, and I don't want to use it - so why not mark it that way?

5. I see a lot of vendors here use free items in their promotional renders - specifically a  certain well known hair item. I wonder how they justify that when the readme clearly states you can't use it that way?