I love my Moto Mods. Sure they are a bit clunky and they don't get used all that often, but I carry them on all trips and just knowing that I can use them is a benefit in itself.
The Hasselblad camera was panned in some reviews but I find it excellent - how on earth can a 10x optical zoom not be an enhancement even before considering the flash. It doesn't take up much space in the little adapted hard drive case I use to carry it round and my only regret (and reason I don't use it more) is the fact that there is no bespoke case for storing it on the phone, nor anywhere to attach a wriststrap to make it more secure from being dropped.
I have a battery pack which doubles up as an induction charger as well as JBL speaker which is great when travelling and using my phone as an internet radio, but the best really (even if TBH it gets least use) is the projector. OK it is not exactly home cinema standard, but it is amazingly good for the size and funcionality and I can happily watch a movie at the same size as most large TVs as long as the room is darkened. And while it is not really up to conference presentations, it does stand in when there is a problem with the tech set up in smaller meetings.
So, yes, the biggest problem is low sales and a virtual halt on development of new mods, both of which mean that accessories like cases are never likely to appear on the market. A pity, this is the best modular system so far and a good attempt by Motorola (Lenovo).