Posted by Aguzo

I think they don't do this, because if they mess up, or you mess up on locking them, then you will blame the devs for not locking your farm properly. Just think of all the people that complain about getting their gralat/s stolen even after "I locked them all."

Lock all gralats option? "You had one job to do, click one button.."
I know it's annoying, but it is probably safer to have people lock gralats individually, than to lose them all if they didn't lock them correctly, or thought that they locked them.