In a recent livestream, the director responded with the following:
"We never had an intention for you to unlock everything in the game,"
"That doesn't really make any sense. It's like in an RPG, in World of Warcraft, you would never try to unlock everything for all the characters. Same thing in any MOBA, you're not trying to unlock all the content for all the heroes."
"We don't expect a player to buy everything. We just expect them to buy the items they want right away."