it would seem to be a good way to give handicap to another player if you have less time to think than the other, better handicap than having less pices... anyway, just an idea for a feature request...
I think, shogi for the Japanese are unlike Chess, I presume. Rather than fighting with time and assuming opponent making a mistake, it instead encourages the players to fight against the position, the board itself. That is how I assume it anyway, as a Go player.
Shogi or Go is unlike chess where a lot of draws occurs. Therefore, a fight against time does not seem that good of a deal for such games. Of course, I do not disagree to have that option available. It is just that it is not conform to Shogi's philosophy, I believe.