Which one of them was a high NHL draft choice? Of that group, the only one I'm aware of who had the opportunity to leave early was Jones after his junior year. He set a great example by playing all four years at UND.
Would it be nice if more players followed Jones' example? Certainly. Is it realistic to expect it? No.
Zach Parise and Travis Roche are two that come to mind.
They are? He had 39 points as a freshman and 47 points this season. A 50-point season is considered exceptional for a junior or a senior. Zajac was just three points away from that as a sophomore.
Also, I don't think you can simply look at a player's stats and decide whether he's ready to move on to the next level. Zajac was perhaps the best two-way player on the team. He played on the penalty kill and the power play, where he excelled.
Besides, it's not up to you or me or Dave Hakstol to decide if a player is ready to leave. It's up to the team that drafted the player or the team that wants a player to sign a free-agent contract. If the team wants the player badly enough and offers the player a deal he can't refuse, who are we to say he shouldn't go?
Murray was a special case.
Playing in the NHL is the goal that all hockey players strive to attain. Given the fact that their time as professional athletes is limited, why shouldn't any college player jump to the pros if the opportunity presents itself and the deal is right?