The fundamental mistake of Simple Made Easy was how many people interpreted them as orthogonal (or even opposing) qualities, when that's not inherently true.

This led to a lot of Clojure code being simple, but avoiding the hard additional work of also making it easy, and sometimes in even making it complete.

The prime example was tools.deps/deps.edn. It largely supplanted Leiningen for new code, but by being simple and minimal, it led to an explosion of ad hoc, custom tooling for 2-3 years afterwards, as everyone rewrote functionality that Lein already had, but tools.deps was missing. (And I say this as someone who once lost a whole week debugging a subtle maven/lein set ordering bug.)