I think part of it may be that the freestuff area has a details and download button.  If you just click download, there is no place to put a thanks...you have to then click details.

Perhaps everyone should have to go to the details, to download, so they can read what the maker said, and also see the thank you form.

...but since you posted I popped over and saw that cool Conference Room, grabbed it, and posted a Thanks!