"you can't sell directly from a Carry-All"
If VIP we get plenty of time to sell up waiting around for the server to re-engage with us. Seems to be one of the few things we can do that isn't so affected by performance.
But that breaks down if we try to move things around; that common error message we see.
"those who do see value in it"
might include non VIP multi box bots or raid farms of old where the junk soon piles up and takes up available space for the choicer items. Perhaps enough has been done by other means to prevent such. It would greatly lengthen the time the bots could run before needing "maintenance" if still so inclined. Hardly worth the investment with the enforced caps and bindings measures that have diminish the game economy so much.
Carry-alls that actually measure up to actual game play usage has not been high on anyone development priority while many players are so eager to accept them in desperation just as they come.
I don't know why many can't just organise there own storage and pack space and think that managing multiple carry-alls is going to be any easier for them!