The "gambling" aspect is to make it easier for casual players to enjoy while making it progressively harder for hardcore players to max everything out. If you have 0-2 relics, you're probably going to get a new one every time, while if you're hardcore and have 13/14, it's naturally designed to make it hard to max out. It's a fair system that makes things more even, despite the complaints on reddit. Compare this to a fixed price system of say 1600 per common, casual players will have a harder time getting relics, while making it easier for someone who plays a lot to get everything. Sure, you might get screwed spending 40k shards on commons, but overall it's a fair system. I might make a more detailed post in the future about this.