Yeah, I've seen the first done with dummy objects as well.
As to the hot spot giving the texture new coordinates, yeah that might be considered a downside, but when using it for visual effect the size would be set to 0.
I made an example: [attachment=0:15w1cph8][/attachment:15w1cph8]
This is especially useful when doing effects to menu's, gui's, window's , etc.
I mean why add the same exact texture just for an effect?