This sounds like a good idea, however in many areas of the UK, for example, there are so many powerlines that pilots would probably suffer an information overload. The warning would possibly be going off so often that it would become counterproductive. We all know what happens then. The pilot turns off the equipment.
I was involved in an RAF trial around 1980 in the Puma, using a device that showed the nearest wires using a magnetic field detection system. The information was portrayed on a small dial presenting the direction of the wires. Where there were many wires it became impossible to decipher where the real threat was.
The device did not enter production to my knowledge.
With any device using a database, keeping it updated is a big problem.
I'm sure it's possible to overcome the problems but as usual it's financial considerations that take priority.