Yep, LG set out to build a module phone and this is the result of it. Unfortunately, it has some build quality concerns and hopefully those can be resolved in production.
I applaud LG for going this route, but I think doing it with the G5 may have been a mistake. It is going to take some time to get it right and why shoot yourself in the foot with your flagship model. They could have come out with a modular design specific model, got the bugs worked out then incorporated what they learned into the G6.
They have accomplished something here and I think it will be copied by others, especially the removable battery design. Metal body with a removable battery that doesn't compromise the structural integrity of the uni-body metal frame. Unfortunately, they will never get credit for it.