Although you can shape the bass and add some phrasing in some pieces.
A couple of weeks ago I played the Sarabande from Bach's 1st Partita for my teacher, a beautiful florid melody over a completely simple, uninteresting bass. My teacher told me to think carefully about exactly how I wanted each bass note to sound, and bingo, my playing of the piece went from boring mush to quite beautiful. The bass is important, even when it's simple and even when you don't want it to overpower the melody.
The bass should be shaped/phrased in ALL pieces!
Ok you are right. But perhaps the bass should not be shaped too much in some pieces because it is mainly the melody that needs shaping.
Well obviously the melody at all times must be at a degreee louder than the bass because the melody is the main focus of a piece isn't it? otherwise I don't think it might be called a melody at all.....while some sections in the bass do require a little attention to shaping, there are others that don't require much like chords, as opposed to arpegios. But this is just my opinion.