Help me understand the deep back formation on short yardage?

It seems more an more common to see the following situation, and I can't seem to understand the logic of it....

A team is faced with 3rd and 1 yard (or less) or even 4th and 1 (or less). In College games and NFL games the last few weeks I'm seeing more and more "I" formations or deep single back formations in these situations.

When your RB is set 4 to 6 yards behind the line of scrimmage, this is setting things up for some 2 or 3 yard losses, which we have all seen recently. Also, in tonight's game, Seattle did this a couple of times and it worked out, but they just narrowly missed taken a 3 yard loss each time.

On one occasion I recall Seattle having 1st and 10 at the 1 yard line, and instead of pounding it in from close range, they have the back set really deep and take a big loss (IIRC).

These situations used to be QB sneaks when looking for a 1/2 yard or less, or the coaches also used a tight formation with a handoff to a fullback and a big puch from the O-line on those of one yard. At times, play action with rollouts also work well.

Anyway, can someone explain to me why the I formation and the deep single set formation is being used so commonly of late in very short yardage situations, and why they are handing off the ball 4 or 5 yards behind the line of scrimmage???