KonstantinosS,
Sure, we also will consider to add Nginx version.
Now we have mixed feelings.
On the one hand, default Pagespeed filters will not satisfy customers. On the another hand, Pagespeed filters seems as a complex feature for customers, like this one:
"inline_preview_images (default=No) Serves low quality images, which are replaced with high resolution images after onload."
there is no known ETA yet