Reading a thread about teams made of less popular heroes on the DC forum got me wondering about this. Why did Lee, et al. so radically retool the Avengers in issue 16 of their original run?
They'd begun as Marvel's Justice League; a cooperative of their world's greatest superheroes (to be fair, a cooperative of almost all the individual IPs Marvel had available at the time). Then, the title took a hard bank.
They resolved the original Masters of Evil plot that had been running through the title for over half it's published life, kicked everybody with a feature of their own out of the book, and filled the ranks with three sympathetic reformed villains. It seems an odd choice. Hawkeye did not seem created as a standalone character, and Quicksilver and The Scarlet Witch were even less so.
Has anyone read or heard of why Marvel made such a surprising choice?