I do appreciate systems that let me change the default myself, since not all do. I've not usually found the png versions to be smaller in size at full resolution, but have found them to be higher quality, which makes sense, but not usually what I want.

@david Is this a surreal question? File size of png is lower and better quality...

@david Because PNG is lossless. It represents every pixel exactly as it appeared on the original screen. With JPEG, even set to high quality settings, some amount of detail is lost and distortion introduced. JPEG is still available if needed, but you can always convert from a lossless format to a lossy one - you can't do the reverse and get the missing detail back.

@david For the transparency obviously

How else you gonna show those hole in your screens? :o

@david maybe less compression and more clarity for higher resolutions?

It's kind of funny, though, JPEG can totally be optimized for it now, with the right methods. Maybe it's one of those conventions that's been followed for so long that no one cares about changing it?

@david so we could have lossless screenshots!

@david Unless you're taking a screenshot of a picture, it's likely that a computer/phone screen will have relatively few different colors and sharp lines (window borders, rectangular panels, etc...). Historically JPEG compression deals badly with these settings, requiring more file size than PNG to reach the same picture quality.