MSilvia:
Because they're more concerned with how their dive gear positions them at the surface than they are with how it positons them while diving.
... they don't give
me any problems at all maintaining any position I feel like in the water column, plus they are more comfortable
for me when floating on surface waiting for pickup.
And a vertical position in the water column is not always 'enviroment unfriendly' as was suggested earlier. If you are maintaining proper situational awareness you will not be bumping into reefs and risking damage to both them and you. Some pass thru's require vertical positioning to negotiate properly without bumpage.
If you are hangin' out away from bottom, why not swim in any position you like?
For me, part of joy of diving is that it frees me from horizontal restrictions. I can swim or drift head down, head up, horizontally looking down, horizontally on my back blowing air rings (great thing to do when at safety stop with a lot of extra air due to different SAC rates).
I have no problem maintaining proper trim and orientation in water column whether I am using jacket or back inflate BC, BP/W, BP with horsecollar, or 'diving naked' with tank on backpack and no bouyancy device at all. But
I do find a jacket style more comfortable at surface.
But once again, that is me, it is important for each diver to find what is 'right' for them and what they are comfortable with.
And watch putting words in mouth or making assumptions or judgements about why
others use the equipment they do, stick to why you do what you do and let others speak for themselves.