They seem to be popular with the "cool kids" into overlanding. They don't seem very practical to me. As someone who has owned a soft top Jeep, and had the top ripped open for thieves to get inside I can verify that they only provide the illusion of securing anything inside. And then you have to consider that soft tops are good for 7-8 years before they have to be replaced. A hard shell cap will last as long as the rest of the truck.
If concerned about weight they still make aluminum caps that can be put on, or taken off, with no help. Cost is about the same as the soft tops too.
