They are also incredibly tolerant to current/voltage spikes because they are purely resistive, which makes them ideal for situations when power could be 'intere

They are also incredibly tolerant to current/voltage spikes because they are purely resistive, which makes them ideal for situations when power could be 'interesting' as they will still function unless they are run well beyond normal limits. So when it's more important that it just works, it's not a bad design. Also soldering them would be least of the cost concerns for the shuttle program, which had much bigger and nastier cost centers.