I think this has been asked several times before, but in the end, I see it as a very limited use case. You do not have enough GW currency to do this every single refresh of every single day as you only earn 1200 per day from GW. so no matter what your stockpile is, you will run out and then the feature has no value. Same goes with the other stores. And those stores have items that you might not want to buy (like training droids from the cantina store).
And even if they do that, you are not efficiently spending your GW currency. there is a slightly higher return on investment on ships rather than characters.
Spending 1600 GW currency on the 4 ships (4x4 = 16 ship blueprints) in that store will net you 608 SSC.
But spending the same amount on 4 characters (10x4 = 40 character shards) will net you 600 SSC.
So moral is, spending it all on everything in that store just to build up a stockpile of SSC is fine, but over the long term, you'll do better just spending it 1600 at a time (you'll still run out eventually, but slower with a better return on investment)
And it also saved development time that they can (hopefully) spend on fixing bugs or new game modes (or, even something unexpected like refreshing TW)