The NHL currently possesses a unique development system when compared to the other major team sports in North America. Unlike MLB and the NBA, the NHL allows players who have signed contracts with NHL teams to be sent back to leagues that do not have a direct, in-season player filter agreement system in place with the NHL, outside of emergency circumstances.
This topic is often brought up in the context of the Canadian Hockey League. Currently, there is an agreement between the NHL and CHL that prevents many under-20 players drafted out of the CHL from playing in the NHL's main minor league, the AHL. It's a truly fascinating system when compared to how other leagues are run in terms of decentralization for the development of hockey players.
In fact, it's in stark contrast to baseball's development system, which requires players to turn pro within weeks of being drafted, and from that point on, remain in their organization's system with direct contact to its coaches and staff. There is certainly benefit to the MLB way of operating, as the big club has more control over how a young player is being deployed to best suit his development.
Should there be any changes to the NHL-CHL agreement, and the overall player development landscape going forward? That depends on whom you ask.