I designed one (CAD is one of my hobbies) that's 10mm thick, 120mm tall, and 70mm wide. To put this in perspective, a pack of 100mm analogs is 23mmx104mmx56mm.
Main features:
1) A hole in the top so I can take a hit, push the PV into the hole to store it, and then push a stud to make it pop up enough to let me pull it out for my next hit.
2) Holds four fresh carts and has room for four used carts in pistol-cartridge-like clips (on one side, under flip lids)
3) Can recharge one battery while other is being used.
Downside:
1) Can only recharge a battery once (to recharge more would require larger batteries, increasing PCC size).
2) A quick-and-dirty estimate from my favorite machine shop: $4200 for a prototype, and perhaps $300-350 each in quantities of 1000.
So, to answer why no one makes a cool PCC:
Everyone has a different idea of what they want/need, so each design will have high costs and low customer base.