On the Shoulders of Giants

Standing on the shoulders of giants is a saying that suggests that we only can achieve what we do because of the foundation already provided by generations before us. This analogy seems especially prevalent when thinking of education, perhaps, particularly science education although most fields can see it. Instead of working out the answers of problems that people faced previously we can start by learning the answers they came up with and then seek to answer the questions that come to light because of this new view.
That seems pretty straight forward but there seems to be downfalls.
First, what do we lose when we don't walk the same path that our predecessors  did? There is a knowledge, an understanding, that you can't get any other way except by solving the problem yourself. And by jumping that step I think you miss out. This may (in most cases) be a worthwhile sacrifice but it is still perhaps something to thing about and gratitude for the previous work should be acknowledged (as the statement in question implies).
Second, in some topics this philosophy seems.... less effective. Some problems appear over and over again, seeming to reappear with every generation. Just from my own observation, and comments from my Dad, these problems that must be rediscovered are moral in nature. Each generation has to rediscover, and redefine in their changing culture, what honesty is, how to balance religion and science, individual roles (economic, caste, gender), etc. Some of this can be taught by the previous generation and some individuals will get it but it seems that as a whole the generation must reestablish itself.
I'm not sure why moral issues are more difficult to be built up on. Maybe because the evidence tends to be more qualitative rather then quantitative. Maybe because often both sides (or all sides) seem reasonable especially in varying circumstances.
In some ways it seems ironic. We, as the human race, are so far ahead in some ways and yet we are continually going over the same ground in others.