The advantages in one view: 

• The ESP-12E Modul can be removed from the adapter at any time because it is just held by the contact pressure.
• The Adapter is so tall, that it can be used on a normal bread board and there is still space for jumper wires.
• The Adapter can be also used just for flashing the module - means a bread board is not required.
• The power supply for the required 3.3 volts can come from a cheap USB flash adapter as it will be sold direct from China for already a bit more than an euro. (these adapters are also able to flash ESP01 modules.
• The Modules remain mechanically untouched.
• It may be flashed in-circuit without removing the module from the bread board.
• The Adapter consists of low cost and simple to get components that can be found often already in the makers part box.

For more details or how to build the adapter visit: https://bechele.de/?page_id=300