I think you failed to understand that what Mophie made wasn't a charging case but a base case for their Hold Force line of products. They did
not offer it as a charging case. The Power Station that attaches to it can be used with other devices. A phone case can't. You're trying to call an apple an orange.
It's not designed to be a temporary solution. It's a different product line for a different use-case.
The 7+ and phones of that size are practically a brick anyway. Adding a juice pack just exacerbates the problem. I ditched a Mophie case for my 5s because it was such a drag to lug around. But if that's what you need, that's what you need.
Glad it was only $10 for a 6000 one I think
1) I very much doubt that Mophie made a Juice Pack rated at 6000mA.
2) Any Mophie product you paid only $10 was either used or counterfeit.
3) All of these devices charge on the slow side or they'd get pretty warm and heat up the phone. The idea is to turn them on before you actually need them.
Mophie has usually made three capacities of cases resulting in three different weights and thicknesses. They're too pricey for my taste, but there should be something for everybody once they ship, if you've got the ching.