Well, that is one way to do it. I think it was necessary for HST because it was such a complex instrument that had to be capable of doing many things, and reli

Well, that is one way to do it. I think it was necessary for HST because it was such a complex instrument that had to be capable of doing many things, and reliably -- because specifically you have to have a mirror of a certain size to make it worth it, and so it calls for a certain level of engineering reliability (and cost). On the other end of the spectrum, the Mars programs (lately) were incentivized to do the opposite -- cheap, fast, and good, even if some of them fail. Different circumstances may call for different incentives.