To me it is a rediculous rule. It doesn't help anyone. I have to either downsize or "down-quality" the images. This happens a lot with textures or a lot of my outdoor images.
I think that at some point we should organize a group and petition to have it raised or domolished. I know this sounds silly, but at a workflow level, their killing me. Sometimes I just say to heck with the images that get kicked back and don't worry about it. I have 600 images and although I should, I don't worry if one doesn't get seen on BigStock.