We decided it was safer to err on the side of caution and put "non-commercial only" as the default, especially since we implimented this long after we had a large number of free stuff links already on the site. It's better to find out that you can use something commercially after you download it, rather than find out you can't. (Especially for people who have dial-up connections.) I think part of the problem is people are mistaking commercial usage for commercial redistribution. Some say in the readmes that you can use the items in any render you want, but not to sell the items themselves. To be on the safe side, though, they are deliberately tagging the item as "non-commercial only" because they are concerned that someone will sell the models and/or textures. I'll ask the admins if we can get something in the wording that makes it clearer so if commercial renders are okay, people will tag their items properly.