So, an amusing anecdote related to your second paragraph - one reason it's taking so long the second time around is everything has to be repeated. They lost the knowledge of how to make rocket stages and engines of that size, and had to re-learn those lessons.

It's also quite important to remember how many lives were lost (or nearly lost) because of "breaking things" in the Apollo program. Something that's not nearly as acceptable today than it was at the height of the cold war. Something that directly implies moving more slowly and being more sure that everything works the first time, every time.