They are shooters. My thought is that players of their ability would help to open things up for everyone else. I think that Beal and MKG are much more talented than Barnes but you cannot deny that Barnes can hit the open jumper.
I honestly believe that Barnes should just make a career out of the corner three. He should always be on one side or the other getting ready to take that shot.
Personally I'd love to land MKG but getting him and Iggy would play havoc on the Jazz as far as shooting goes. Since getting MKG and another lottery pick is highly unlikely I figured Iggy and one of the two shooters you mentioned. That improves the team in a much more balanced way. Especially is we get Nash who is a shooter as well.