They should leave things alone. In fact, I'd even take the age eligibility rule out as well. If you are 32 years old, enter the NHL and can put up Ovechkin/Crosby numbers, you should be a Calder candidate. And in most years, you'd probably win.
Age should always be a consideration when handing out ROY honors. A few years ago in baseball, the AL ROY vote was close because Hideki Matsui was much older than Rocco Baldelli. One came from Japan, the other from A ball. Personally, I like these discrepancies. It makes the rookies all the more fascinating.
As for the nauseating Ovechkin/Crosby debate, I think most sane, rational Penguins/Crosby fans would suggest the following: The Calder is not the award that goes to the best prospect entering the NHL. It's the award for the rookie that had the best first season in the NHL. That's Ovechkin.
Crosby can take solace in the fact that only 3-4 other rookies would have ever beaten him in the history of the game for the Calder...Ovechkin, Selanne, Gretzky (had the NHL not had a vendetta against the WHA) and Orr. That is pretty awesome company.