There's a fantastic story relating to this in Roving Mars (about Spirit and Opportunity). The final design had both lander-departure ramps and the now-iconic f

There's a fantastic story relating to this in Roving Mars (about Spirit and Opportunity). The final design had both lander-departure ramps and the now-iconic foldout solar panels, but it was initially rejected as "gold plated" on budget and weight arguments. The only reason it eventually came to pass was the realization that while the foldout solar panels were overkill, their removal would be worse than anticipated and bring the mission under minimum lifespan. Steve Squyers talks about how he was told this as "terrible news", but realized that for him it was wonderful. There was no way NASA would accept luxuries, but if the 'budget' design wouldn't work they were willing to move up a notch. So the incredible longevity of Spirit and Opportunity is largely a function of a low-cost design that broke down too late to salvage. It almost killed the whole project, but got record results once things went through.