I recently read an online article about the spread-eagle position in bondage:
The spread eagle tie is fairly popular in bedroom bondage, especially when the victim is naked, because it leaves her vulnerable to various sexual activities, including tickling, sexual stimulation, and orgasm control, while tied up, cuffed, or otherwise restrained, to prevent her from interfering with the progress of the activity.
The complete helplessness and vulnerability of the partner in this position allows the dominant partner complete freedom with the subject, able to tickle any part of her exposed body. Tie and tease and orgasm control are popular forms of play in a spread eagle tie, where the legs are securely spread and the dominant may provide sexual stimulation at will.
This position is also popular for some adult BDSM games, because it leaves the subject open for various sexual activities. In the adult industry, tickle torture and orgasm torture (a BDSM practice of continuing stimulating the clitoris producing multiple orgasms) are common in this position, especially with additional restraints, as the subject is totally incapable of resisting or even closing her legs.