It's still a pretty simple system with direct detect optics, especially on such short distances. Transceivers are really inexpensive for relatively low throughput (<40GE) applications.

They do very thorough HFSS simulations for fighter jets, having RF noise immunity without having to use heavy shielded wiring is a great benefit.

Splicing can be rough, but it's by no means impossible. With the right equipment, you can expect <0.3dB loss from a splice. That's not a lot in these very short links.