Why not return to that formula?
There is an argument that the value extraction out of the network is bad for long term success. Play a game for free, get a rare card, sell for $500 and pull that valuation out of Splinterlands. It's like liquidity leaking out of a ship.
I understand your point however, don't get me wrong. Playing to earn cards to play more was the core mechanic which brought a lot of players. I think Foundations is done well, super duper cheap cards which you can still start to build a baseline collection with.