Jack and Luke were much better players overall and had a much higher impact on the game. The Devils are trying to be contenders, not gift players spots in the lineup when they're barely NHL caliber.
Do you not understand that players bust? Do you think every single player with "potential" will figure it out if you just force them into a top 6 role without having them earn it? It's fine to admit that Holtz was a bust of a pick and the Devils are choosing to move on now and trade him for a player they think can fill a bottom 6 role moving forward.
How do you know what Cotter could have been had for? You do realize that Holtz's value isn't much right? Go look at some other underperforming top 10 picks and what their value was (Zadina, Kravstov, Jost, Puljujarvi, Alex Nylander, etc...), you just don't seem to have much grasp on what underperforming top 10 picks go for in the market.