Not an expert in this area, but I think that that "just" is hiding a lot of complexity. Plus you also need some remotely operated robots to mount the replacement.
Stationkeeping is not free, satellite monitoring is not free, and any replacement to any component is now a multi-year, at least 1+ million dollar affair (or most likely a complete replacement, since not many satellites have done in-situ repairs).
r&d sure, not sure about ops as you can probably just detach a faulty module and launch a replacement.
Not an expert in this area, but I think that that "just" is hiding a lot of complexity. Plus you also need some remotely operated robots to mount the replacement.
Stationkeeping is not free, satellite monitoring is not free, and any replacement to any component is now a multi-year, at least 1+ million dollar affair (or most likely a complete replacement, since not many satellites have done in-situ repairs).
Relaunching is effectively operational cost.