The Power Ballad is probably one of the most controversial things to come out of the metal scene in the 80s. As a metal fan you either loved them or hated them. Most die-hard 80s metal fans hated them. While the formation of the 80s power ballad in general was credited to bands like REO Speedwagon, the instigator of the takeover of 80s metal by power ballads had to be Mötley Crüe's Home Sweet Home.
There were other power ballads before this one (Alone Again by Dokken for example), but the success of Home Sweet Home in 1985 really brought the copy cats out in force. Pretty soon the major labels were demanding that all of their metal bands include a power ballad on each album to try to recreate the success of Mötley Crüe's Theatre of Pain album.
During the late 80s, power ballads by groups like Whitesnake, Poison, Skid Row, and Bon Jovi were regularly in the top 10 on the Billboard weekly hot 100 charts. These were heights metal bands had never seen before. Below are some of the top charting 80s metal power ballads during this period based on the end of year Billboard Hot 100 Charts (you can click on the name of the song to watch the video):
Many credit this over abundance of power ballads to the reason that the popularity of 80s metal died off quickly in the early 90s. To be sure, the power ballad brought in a lot of fans that were not normally into the 80s metal scene, propelling the metal scene to the top of the charts. Even thrash metal band Metallica put out a power ballad (Nothing Else Matters in 1991). However, this alienated a lot of the diehard metal fans who were turned off by the slow ballads. When the pop scene moved off towards Seattle and the 90s alternative music sound, there was no one left to stop the free fall of the pop metal groups. By the mid 90s, a few metal bands, like Bon Jovi and Aerosmith, had maintained their popularity to some extent, but most of the top pop metal bands from the 80s had disbanded or been dropped by their labels.