Since the [X] Button that delete a world is centered and big, it is a "Call for action" button. so the human mind makes you wanna click it.
But, deleting a world is not something that you want to do by mistake... you did implement a confirmation which is obvious, but I am talking about preventing pressing it by mistake.

Today my lovely daughter mistakenly deleted our more than 150 hours invested world without option to undo.
(It happened also to a friend of mine by mistake)

Think about the amount of children that use their father's ipad/iphone, run MCPE, pressing the "Call for action" X button and then pressing one of the two buttons. it's 50% chance that huge amount of hours are going to be wasted in one single click.

I will really appreciate if you will see this in a positive way.

Adam.