I believe it is due to an unwillingness to make a concrete statement. A full stop is strong and is equivalent to speech in a flat and confident tone. The ellips

I believe it is due to an unwillingness to make a concrete statement. A full stop is strong and is equivalent to speech in a flat and confident tone. The ellipsis seems to stand in for short disclaimer phrases like "by the way", "in my opinion", "in case you were wondering", etc.