I think another point that should be made is the Vision isn’t just Stark’s (grand)baby. It has the Jarvis protocols from Stark, vibranium which is the same material as cap’s shield, and the process was powered by Thor’s lightning. Natasha secures ‘The Cradle,’ Barton flies it out of Seoul, and Banner co-created him with Stark. So, i think Vision shows that legacies fail when they are carved out in isolation and privately (which was why Ultron was a failure), and that only a shared vision founded on cooperation will avoid megalomania.