From what I've seen, a lot of games include an "8-bit" sort of graphical style. In this case, often the user has to set the image filters so that it uses nearest-neighbor scaling when scaling up, otherwise it makes the image look blurry and unattractive.
However when scaling down, linear scaling is indeed favorable as to make sure the image doesn't look like a fragmented mess of pixel vomit.
I can understand that the logic behind making both filters "linear" by default that the image would be smoothed out, but LÖVE's scaling isn't exactly favorable going up, especially considering the common standard of "8-bit" graphical styles in indie games. Obviously you can set the default image filter yourself, but regardless, would it not make sense to set LÖVE's filter to a default that works in favor with more game devs?