The inside of your vice jaws are flat. If you grip the hook where the wire is level the grip will be all along the edges of the wire. If you grip the hook where the wire is tapering then becoming straight the grip will only be at either side of the point where the taper begins. Here is a sketch to illustrate what I mean.
Untitled-1.jpgAs it takes greater pressure to grip the wire at one point it will result in wear and damage to the vice jaws much quicker than gripping it where it is level. It is also pressure at this one point that has resulted in Joe's broken hooks.

Some people ignore this for the convenience of hiding the hook point. Understanding this though, leaves two positions. Learn to miss the hook point and have longer life of your vice jaws. Don't learn to miss the hook point and replace your vice jaws more often (not more often than anyone else, but than you would if you did it the other way). You pays your money and takes your choice.

Cheers,
A.