Eli5 why does the US still use a bomber from the 1950s when they have built two newer ones since then?

Question

Eli5 why does the US still use a bomber from the 1950s when they have built two newer ones since then?

In: 7

Answer 1

B1 = aluminium performance racecar

B2 = carbon composite performance racecar with ADHD

B52 = truck