In case you haven't been keeping up to date:

Q24. Please let us know if you’ve finalized the number of slots that will be added in the second Inventory and Armoury Chest expansion.

A24. Unless we change from the current method, we do not think we can add any more slots. There are other factors to consider, such as managing inventory through the upcoming app, so this will take a little more time. It would be difficult to implement it by 4.1, but it is not so far off.

Source

Also, something something customer feedback, something something issue doesn't concern you so other people's concern are invalid/unimportant.