It is very strange, these things they are saying. I am equally confused and kind of think this is going to end up a net bad for everyone involved. But attempting a favorable understanding of these changes makes me
think there are two issues that are trying to be addressed here that they didn't explain very well. I think they are trying to say that they at trying to prevent both under-prepared and over-prepared projects.
One, they don't want people who haven't built a physical prototype yet. Say I wanted to create a modular synthesizer based on children's blocks. I should be able to scrape enough money together on my own to get the basic prototype done. If all I had were renderings, that means I really haven't done due diligence on the project yet, I'm just throw stuff against the internets and seeing what goes viral. I know I personally would like to see more action and less talk out of people and their projects (and I am guilty too), so that is one thing.
Two, they don't want people who are just looking for VC to buy their first factory timeshare in China. If you are that far along, that you have the board completely figured out, all of the design files are ready to go, then what you actually, really need is investors or credit.
Kickstarter is trying very, very hard to avoid the possibility of appearing as an investment system or a lending system. If the lines get too grey and the "average public" starts to think of them as either of those things, they are going to get a LOT of regulatory scrutiny from the FTC. so they promote this notion of patronage. They are essentially trying to democratize the system of business that most of the great artists of antiquity worked under. Hence the emphasis on "projects", not "products", or "events". The money your are receiving is supposed to pay to feed you, house you, warm you, while you pour all of your time into this project.
Now, that doesn't seem to really jibe with the "no concept renderings" rule. The linguistics kiosk was nearly identical to the original concept rendering I made in Blender, that was a significant factor in getting the client excited about using us for the project. I think renderings can be very practical and there should not be any more risk in promising features in a rendering than promising features without a rendering. Also, sometimes you need a bunch of time to finish that prototype. It just doesn't always work to build things in your spare time.
So perhaps the idea is that, if you are in prototyping stage, you should be able to sell yourself, not the product, because you are selling your use of time, not a product. Remember that this site was conceived first for artists recording albums and making statues and the like, not for engineers to get investments. It is a malleable system, so they are trying to make sure such projects fit that model, so as to not drown out the "aht".