You could also get them from crucible, about 3 of them but were a bit rare. You could get about 9 Strange Coins by doing nightfalls once per character but the chances weren't 100% since you only got rewarded 1 item, incluiding exotics or legendary motes. In Destiny 1 the currency was called 'Strange Coins' and every exotic that Xur brought costed around 33 Strange Coins if I'm not mistaken.
So im not here to spread any hate in the current system, just suggesting changes for the better. Before I dive deeper into what I think, I just want to adress that I played D1 since it's launch and I've experienced in a way what the game has to offer regarding this topic.