There is also the issue of what happens if you are undraftable after a year? Do you get to stay on the team and get paid the same, or do they basically make you a free agent, where you probably get a normal G-League contract worth about $50,000 or so?
Just my opinion, but I think this was basically to make the NCAA start allowing players to profit in one way or the other. The NBA doesn't want a development league, and they don't want to be sitting in high school gyms either. What they truly want is for colleges to do the enticing, so that they can foot the bill for development, and the NBA doesn't have to do anything. The evidence for this is how much they pay regular G-League players. If they truly wanted a development league, they would pay enough to entice the really good players to try to get there through that versus going overseas.
At the end of the day, it all comes down to numbers. With the average NBA career hovering around 5 years, it basically means you really only have room for 2 players every year, and guess what, that's exactly how many players you draft a year. So as a team, you only want a few players in development in case 1 of your picks doesn't pan out. There is only so much room on an NBA roster, and it is financially better for those teams to see guys against good competition, and be more sure about their picks than trying to develop a guy you took a chance on, who in the end may never develop.