It is also nice to know that I can print replacement parts and that my replacement is pretty much identical to the original.
Managing a printer farm sounds like a lot work, but they did do that work and can reap the benefit that prototyping and manufacturing are the exact same process. It's like saying "why does Google have all these servers when they could just buy them from AWS?" Well, they got good at building datacenters before you could just rent a datacenter from Amazon. If you're good at something, keep it up!
Another point is that it allows you to print spare parts for your own or a friends printer if something breaks, or print upgraded parts if they tweak the design.
a) injection moulded the parts
b) provided all of the parts as 3d models for for spares
though. There's something else all you guys are being weird about.
Is it the IKEA effect (https://en.wikipedia.org/wiki/IKEA_effect) in action?
I was interested in upgrading my 3d printer to a prusa model.. but... the having the parts being built to subpar-precision using a FDM printer in a Czech 3d printer cluster didn't seem super exciting in itself...
None of the parts need to have tighter tolerances or higher precision for the Prusa printers to work well.
The fact of the matter is, print quality on basically any FDM printer out there can be dialed in and be really damn close. Even on the cheaper ones. The differences are more on print speed, bed leveling, crash/out of filament/etc. detection, recovery after power loss, etc. And none of those are affected by whether or not the plastic was injection molded or 3D printed.
In exchange, they gain a lot of dogfooding on their designs, including through physical and software upgrades, etc. They get to do a lot of testing on how well things like their powder coated sheets hold up to extended workhorse levels of printing.
And yes, some of it is a bit of marketing - Our printers are so good, we print them on themselves! - and the adhering to the whole RepRap movement, but there are a lot of benefits that they clearly believe outweigh the downsides.