Why don't more dive shops display more (any?) BP/Ws? Because most divers don't buy them.
Why don't divers buy more BP/Ws? Because they are never introduced to them in class.
Simple
That's exactly right.
Our local dive shop in Rohnert Park has an Apeks plate (just the plate) hanging on a peg from on of the center holes down low and to the side on the same wall as all the big fluffy. poofy poodle jackets diplayed high and proud.
I got into a discussion with the owner about how sales of the plate were going. He said he hadn't sold one in over a year and the thing is still sitting there. I asked him if he thought about rigging it up and letting one of his instructors use it or anybody for that matter, or just rig it up so it looks useable hanging on the wall. He said he didn't want to put the effort in and tie up any more money into something that nobody would buy. Plus I think he doesn't know how to rig one (between you and me)
Here is a classic example of not cultivating a market. If he was serious about selling BP/W's as units all set up he would need to spend some money up front and get his instructors in them, students in them, divemasters in them, but he won't. It's too easy just to sell a ready to go jacket out of the box with easy adjustments and they get to make 100% on them right then. No assembly required and no special or added training.
It would be interesting to do a controlled test sometime. This is all purely hypothetical.
Alternate 1:
Take a group of ten people interested in taking an open water course and take them all into a dive shop as a group to sign up. A group would be picked that have never set foot into a dive shop, so they wouldn't know what a regular dive shop sells or is supposed to look like.
Have the showroom set up with only a BP/W system as the only BC they will be using. Go through the class and the pool work. After they have had time using and getting used to the BP/W introduce them to a jacket bc and let them try it out. Include a peak performance buoyancy session in the class and make sure everyone is weighted correctly before going out to the ocean (in both rigs) and understands the concept.
Once at the ocean the students would be given the choice of using either rig for their open water check out dives. The instructors and the four divemasters would remain wearing the BP/W throughout the pool work and ocean dives. As part of the experiment the students would be required to purchase one of the two systems right after they get certified.
Which rig would the divers ultimately choose for their purchase? assuming both units were priced exactly the same including weight systems.
Alternate 2:
All the same as above except the instructor and divemasters use the BP/W in the pool
then they all switch to the jacket bc for the ocean dives.
No reasons or discussions would be allowed to the students as to why this is being done.
What would be the difference in the end purchase with this change?
Alternate 3:
The students walk in to the dive shop and all they see are jackets. They start in the jacket then half way through are introduced to the BP/W. The intructor and divemasters change rigs with them. During the ocean dives the students are given the choice of using either rig, except half of the divemasters use BP/W and the other half use Jackets. The instructor would split the 4 check out dives equally between the BP/W and the jacket.