Why is the B787 one of the few aircraft with electro-thermal wing anti-/de-icing? While I was searching for a listing of aircraft with different anti-/de-icing methods - especially for electro-thermal wing anti-ice - I couldn't find any information about other aircraft except the B787.
Is there any reason, why other methods like TKS or using bleed air were prefered in the past? 
Are there any studies related to the pro's and con's of the different anti-/de-icing systems?
Partially because 787 has no bleed air available for any purpose. Its engines do not draw bleed air traditionally. Any pneumatic system draws air from other pumps. Hence electro-thermal wing anti-ice system is needed since no bleed air is available.