Because the store offers the range of rewards that were previously in the GC reward boxes. The difference is that the player can now use the rest of the currency to buy the things that are currently helpful to them, in addition to the Omicron mandatory purchases, instead of what the game rolls.
It is similar to the change in raid rewards a few years ago. Yes, you get a few fewer rewards overall, but you can choose exactly the ones that will help you, instead of getting the 4000th blue piece of equipment in the box.
It would help to familiarize yourself with all the information first, instead of always complaining straight away