I disassemble my BP/W at the end of the diving day/trip. Since my STA is weighted, separating it from the BP makes it easier to handle during rinsing. Freeing the wing makes it easier to rinse and dry. I live in a small apartment, so I am concerned about efficient storage of the gear afterward. Breaking everything down (not much more than the removal of 2 wingnuts) also enables me to store the stuff in a small container without the fear of damaging my wing by a "pinch-flat." The wing is stored on top of all of the heavy stuff. I'm sure that if my living situation were different (large house with rinse tank and more dedicated storage space), I might not be so inclined to break it all down.
I can see how you might get annoyed with having to reassemble the rig before diving. But really...it takes very little time to position the wing, line up the STA, and tighten the wingnuts. Personally I don't mind it much.
BTW, I think during the rinsing/cleaning stage is one of the times when the design of a Deep Sea Supply BP/W really shines. My gf loves hers. The wing separates from the BP very easily...and there's no STA to worry about.