Wow, sorry to hear you experienced all these issues. Sounds like you must have had quite a bad luck with the device you got. In the 1,5 years I have my FP2 I didn’t have any issues, except for the cosmetic problem of the case disintegration.
But well, any manufacturer of electronics has some devices with failures. I guess to reduce that to zero would increase costs substantially, not just by 100 or 150 €.
From my experience with FP1 & FP2 I can only say that the phones are much more reliable than the other smartphones we had in the house, from well-known vendors. So I think in regard of reliability Fairhone is on a good path. According to once presented DOA statistics (I know it doesn’t say much about long term use; but its a number we have), FP also performs within industry average.
I agree with the other posters before, maintaining a modular design makes sense. However, as I already thought when FP2 was released, in my opinion modularity to such an extent (7 modules) only makes sense when you can also upgrade components. Otherwise I would reduce to only those parts that most often fail/break with smartphones, such as battery, display, usb-socket. If the modules are not upgradeable, I see little reason for other parts to be located on individual modules. I would rather use that space for a bigger battery then.