There used to be an option to buy bonus heroes (without all the extras of the reward track) for gold only. That option is gone. I understand why, people maining BG still made gold and had nothing to spend it on so probably nobody bought extra heroes with money, while Blizzard still invested money in extending the game mode. They had to find a way to get some return on that investment.
But outside of BG nothing has changed (except the number of mouseclicks) and in BG all the rest has not really changed.