Let's look at what going in the bass clef. You are playing a B for beats 1 and 2 and then playing another B on beat 3, but you also play a D for beats 2 and 3 in the bass. Because you play the D on beats 2 and 3 and the B is also being played on beats 1 and 2, the rest is used to show you what beat to start playing the D.
Without the rest in, the notation would tell you to play the B for beats 1 and 2 instead of 2 and 3. The rest is necessary to show where to play the D. It looks odd, but it's the best way to notate what is happening.