News Microsoft Reportedly Showing Off Dual-Screen Surface Internally

Giroro

Splendid
Dual Screen laptop concepts have been floating around since at least CES 2010, but they never materialized as a real product for what I would hope are some pretty obvious reasons (much lower batery life compared to single screen, lack of keyboard/trackpad made it almost unusable as a normal laptop, they don't really do anything that a normal laptop can't, nobody asked for it).

Back in 2010, tablets weren't even very good. Now tablets and convertables are excellent, polished, and common.
So the same questions remain:
What does this concept do better than existing laptops/ tablets/ convertables?
If the bottom screen is primarily going to display a keyboard and track-pad, then why should people want that over a normal, cheaper, and more comfortable keyboard?