I'm for it as long there's a cap on how many players you can place on IR. That way, you don't have teams gaming the system. For example, let's say the C's signed all these free agents, but stashed Bradley, Semih, and Luke on IR to keep their rights for next season. Can't let teams take advantage of the rule. Maybe if you let each team place one player per year on IR? Right now there's zero, so even one player would be an improvement.
Make it similar to the NBA's injury exemption but add that the player you place on IR cannot return that season. Maybe even a stipulation that you must have a transaction in place where the spot is needed? No placing a rookie on IR in December then leaving the 14th roster spot open for March buyouts.