Old gallery had more materials, this is true. But, there were many materials which were not matching their thumbnails anymore. Or, practically useless, extremely slow ones. So, we tested them one by one and had to eliminate 75% of the materials. Fixed some of them. There are currently more than 1000 materials which are working as expected and we have still some of them more left to tag. You will soon have a very flexible search system. And later, we will evaluate your new material submissions. Unlike in the past, every submitted material will not appear on the gallery. We need to keep quality and usability. So, it's not like "Look, I have a material with displacement for rendering a CPU cooler and the benchmark is 2" anymore.
Thank you for you your patience!