Re: Why on earth didn't they just use standard components?
Multiple manufacturers != long manufacturing life. Batteries are particularly awkward for the Fairphone project, I suspect - they deteriorate progressively rather than just working or failing, so they will always need replacing eventually - but no-one (other than Fairphone themselves) have any commercial incentive to keep making them in the same form factor indefinitely.
Fairphone have had a serious crack at addressing the obsolescence problem inherent in devices like phones, and I applaud them for it - I have a Fairphone2 which works very nicely. But there are limitations on how much it's possible to achieve, partly because ethical trading practices are always undermined by the nature of raw capitalism, and partly because not everyone is lucky enough to be able to pay a premium for a sustainable and/or ethically-sourced product.
So we pick and choose our allegiances and priorities to suit our whim - I buy my organic veg from Waitrose and my electrickery from Ecotricity, but my beer comes from Lidl. :)