I too am shocked by the new restrictions here on Renderosity. Most of my images fall into the 1600x900 size range and as of now most of them would not be accepted by this site. I do not intend to render smaller images.
What is especially confusing is that the 4000x4000 512MB limitation has existed for over 10 years. Storage technology has much improved since then, this site should have a hundred times the capacity it did when the old rules were established.