As I say - there's a good reason why that's not been done - in England, 40-over cricket is considered more crowd-friendly.
Presumably, in Australia, West Indies etc. crowds are happy to come to 50-over domestic matches (obviously not in the numbers that attend ODIs, but bigger than those who attend the League).
As I also said - it's a difficult balancing-act. I don't think the solution currently being tried is the right one, but nor do I think there's any magic-bullet.
RIP Fardin Qayyumi (AKA "cricket player"; "Bob"), 1/11/1990-15/4/2006