I have one thing that i think would make the store a whole lot easier to use. That one thing is being able to see your runes in the store. Every time i wan't to buy some runes, i have to constantly go back and forth to the runes section in my summoner profile, and the runes in the store.
The easy fix, would just simply be to have a button in the runes tab in the store that allows you to access your runes, and then simply add a button to go back to the runes section in the store.
This would save a lot of the time wasted making sure you have enough runes, and gives the store a ton more accessibility.