A well-done tie compliments the female body. The symmetry, patterns, and way the rope accentuates the curves of the buttocks, or the breast is truly art.
While I enjoy seeing a woman tied, and have taken up to 15 minutes to put her into a pretty, or secure bondage, I have not had the patience to study nor execute a shibari scene.
Mostly I enjoy the position for the vulnerability that it exposes in the woman (not necessarily legs spread, but the underside of the arm makes a woman look - and feel - more exposed).
I've been to one or 2 demos on ropes. Some at the NELA (New England Leather Assoc) meetings at a hotel. One thing that was emphasized, was DO NOT SUSPEND anyone, unless you have extensive experience, have capable safety scissors handy, and preferably have an assistant who can help quickly and safely take someone back down.
For me, the woman is tied so I can avail myself to her tender areas - tease, mild torture, flog, and stimulate to a wonderful orgasm where she is "forced" to absolutely let go.