Unfortunately the current NHL and NCAA rules regarding these players are not conducive to this.
First because NCAA athletes are not allowed to accept professional money in any capacity, they can't even be given a plane ticket and lodging to attend NHL training camp. They basically need to pay their way to training camps themselves, even if they are going "for the experience" and have little chance to make the team.
Second, an NHL team is at risk of losing the rights to an NCAA player if they go unsigned for too long. It is something like if they aren't signed a year after their 4th year (or when they get their degree or something like that), then the player becomes a free agent. So a player who stays at College to finish his degree doesn't have to wait very long to circumvent all the RFA rules and gets to pick where he wants to play, and for more money then a typical RGA contract.
So this puts NHL clubs in a position to pressure these players to sign early and before they finish their degrees. The NHL teams want them in their system, with their trainers and training camp to make sure their development progresses. Also they will dangle NHL contracts / money to have them leave college early so they don't risk losing their draft picks for nothing.
As more and more NCAA players make their way to the NHL, both the NHL and NCAA need to revamp these rules for the benefit of the young players.