Spalding, not everyone SHOULD use the VH systems. For some, their singing techniques do not lend well to this device, while for others, such as UD, it's a fantastic tool.
As I stated above, it's something that you must learn to use, and the learning curve is not easy and very steep. Some folks just never get the hang of it, but some, such as myself, and many others I know, love what can be achieved within a song that cries out for vocal harmony in some segments. When the Beach Boys sing Little Surfer it's the incredible harmony that brings this song to life. Same is true for many other songs, old and new. How about the Sons Of The Pioneers with Cool Water, a song of which only has a few segments in harmony, but that harmony adds so much to the song.
There's a lot more to singing in harmony, electronic or live, than just adding an extra voice or two to the primary or lead vocals. Learning how to utilize this asset to the fullest extent and making the music flow naturally is what it is all about. Unfortunately, there are those that do not understand this and consequently, give the harmonizer a bad reputation, one that is not deserved.
All the best,