That's because it is the real life way to go about winning battles and wars. Apply overwhelming firepower from a position of cover/concealment. Age old tactics.
Yup, this class definitely makes alot of sense. So much so it can be hard to get away from. You do massive damage from afar with basically no chance of being touched. I feel almost guilty (and a little bored) killing fiends with a silenced sniper rifle with out even getting at CAUTION alert.
Enclosed spaces tend to be a little more difficult for this build, but high sneak is such a trump card.
Sometimes I think agility shouldn't govern both guns and sneak. Not that it doesn't make sense, it just that sneak and guns are both very powerful elements Fallout:NV (and in the series).
I really wish they had stealthy snipers attacking you from out of sight. That might even the odds