This reminds me of when they changed the hotbar cool down animation. People had a cow when it was changed and people screamed for an option to keep the old-style cool downs. SE gave a response about the technical reasons why they couldn't provide an option for the old method. People continued to complain for a short while until they became accustom to the new style, realized it was indeed an improvement, and moved on.

The same thing now with the inventory UI change. Why should SE provide an option for the old inventory when it's more flawed then the new? It displays 30 more slots in the first tab but it still doesn't display all slots in one tab. That's what people want. Not the old inventory. If SE's going to provide a third option, then that's what it should be. To display everything in one tab. And that's not what the old inventory did.