G15 irons are Game Improvement Irons
Ping know that you only score points in golf for getting the ball in the hole rather than for how nice your clubs look - and that's why they've made the G15 irons as playable as possible. Their main concern when designing the G15s was to make them as forgiving as they could and this means a large head, wide sole, offset, deep cavity and ultra-high MOI. However, for some golfers this puts them off because they simply don't like the look of the clubs - even though they know they will probably help knock shots off their game.