Spring is pretty lean as long as your use case is typical and common - you can practically setup most of the foundation just via config. However, anytime you have to deviate from the typical, the complexity of the Spring framework underneath starts to show and the beans and boilerplate start to grow pretty fast - not unmanageable but not exactly lean either. Fully agree about the ecosystem.
At the same time, this flexibility is a core feature of Spring. In most other frameworks, when you have a use case that isn't supported, you're entirely on your own. Or, worse, end up with in-house patches and hacks to the framework itself. Spring is an integration framework, and so closer to a framework for building frameworks. It just so happens to have a bunch of well supported ecosystem defaults.
