One more to add. Current commercial aircraft can jettison fuel to reduce the landing weight and minimize risk if the structure is compromised. Hard to see how this design would.
Jets also constantly lose weight while burning fuel. This results in airliners flying higher and more efficiently as the flight progresses. With batteries, you're kinda stuck with the weight.
And it's true that airliners take off with more weight than they are speced to land with. They have to dump fuel if landing before burning it off.
No reason I can think of why you can't drop empty batteries in an emergency situation. In fact, you probably want swapable batteries to begin with, don't want to waste time on the tarmac charging up.
1) Aircraft cost is proportional to empty weight.
2) Range is proportional to total stored energy / drag and drag is proportional to weight. If you have low specific energy, you cannot go far.