Shifting the draft age from 18 to 20 has been a personal dream of mine for a decade. It's far easier to get a read on a player at 20 instead of 18. Thus, it would be a better draft than the crap shoot we have now. It would also bring players to the NHL who are more likely to be ready.
In my opinion, it would have a major benefit on the overall quality of the game. Why? Players these days are not properly developing. Due to the 18-year-old draft and over-expansion in Canadian Major Junior and Canadian Junior A hockey, players are entering junior a year or two too soon. Instead of playing in midget when they're 16 or 17, they're being rushed to junior. Thus, a 20-year-old draft would help keep players in minor hockey until they're ready, instead of being ruined by coming up too early.
But it's a dream. There's no way it would stick. The draft will be stuck at 19, with an opt-in for those who are 18, (which most players take), for years to come.
Scouting is far better and far more thorough than it was 25 years ago, that's why the number of busts would be reduced.