The announced business model is why I uploaded my stuff here. I started selling content on some sites including Renderosity 5 years ago. With great success, by the way. But I stopped because of several reasons. The main reason: I wanted to make content, not "Poser-Packages" and advertising pages. So I looked for another way but the usual Poser stores.
There is a lot of crap that is sold in stores. It's hard to say if a product is useable or not just from the advertising pages (some producers are better with creating advertising pictures and icons than creating content). My idea with this site was: Try before you buy. Good content free for non-commercial use. And I bet: I'm not the only one with something similar in mind (providing things for free to make money as soon as possible).
This times all sort of digital content is what a classic product was before. This is the reason why strong copyrights are implemented. For music, videos, pictures and even digital 3D-products. Most new business models are made around products created for free from others (called Web 2). ShareCG's original business model is the only fair model with a good chance for the long run, IMHO.
I'm a content creator and I'm interested to make money at the end. Similar to what ShareCG has in mind. Doing something good to the people while staying in business.
ShareCG's problem is not the business model itself. The site owners are just not able to implement it.
There are some basics (web standards) common for all business sites on the web. Nothing special, nothing new, nothing fancy. Forget about the dream of "easy access without email-verification". Forget about a working rating system. Forget about a high quality community (there are enough other places doing this job better - you aren't able to force it). And: Forget about the dream of "no control". Concentrate on the only UPS (unique point of sale) you have: Your advertised business model.
Accept that Poser content is what pays the bills. You may be able to develop this site to another direction - but not tomorrow, not next week. People making videos or music will find a mutch, mutch bigger audience on YouTube and other places. "Real 3D artists" are homed on well known other sites. You are left with a million of Poser users - take them.
Your offer: Storage for free content - isn't that attractive. Storage and traffic becomes cheaper every day (internet providers offer "unlimited traffic" starting from 10 Euro per month). There are a lot of other places to store a ZIP file.
As said here before from others: If content providers are invited to become paid "valueable members", the SPAM problem is mostly solved. If only downloads are counted and a download requires to enter a code before it starts, cheating isn't possible anymore. For other things (including copyright issues): Make sure "Flag as Inappropriate" works. There are enough people around having an eye on anything uploaded.
Anything happend to this site isn't new or surprising. So just make sure you have at least one people in your stuff with a good knowledge about the common basics to create a business site.