All that's being asked for (if I understand) is convert to JPEG on export to reduce the download size for certain images... ...it just could be an option to further compress JPEG suitable images when exporting.
What I think would be really useful, and is what HotGod is probably suggesting, is not just a JPEG compression option on export, but a way to link an manage different file types as textures.
Like HotGod said:
All I asked was to keep the source file intact. If the game designer uploaded a jpeg it must have been in purpose. The same goes with Png.
I simply use both formats cause I know what format gives me the best possible outcome.
I share this very same desire.
What comes into my mind is the way 3D softwares manage textures. They normally have a texture slot that you can set to any image you want, using any of the supported formats. They normally also include some options like ignore or invert alpha, use mipmap, interpolation mode, etc. Then the image gets linked to the texture slot.
C2 does almost the same thing, the main difference is that it automatically converts any image you load to PNG. And that is what causes conflict with the designers intentions when using different image formats.