Canvas group is a good way to get blurry and pixelated gui. I experienced this when I put a canvas group in a scroll frame with a bunch of elements for a list. But when I put the scroll frame parent as canvas group the low quality seem to fix itself pretty well. Basically it starts to look real bad only if the size is larger than the screen size from what I experienced.
Roblox should definitely add a GuiEffect instance to make stuff blurry or pixelated that is official. A pixelated transition between menus would be cool for like 8-bit type looking games.