The concept of inner bean has revolutionized the industry for Java developers, providing them with more flexibility when it comes to Spring MVC applications. An inner bean is essentially a bean that exists within another bean definition and can be configured from within this definition. This allows a programmer to configure different beans in different ways and provides the means to create specialized implementations of beans that are specific to the application being built. As helpful as this feature may be, it does have its drawbacks. For one, configuring complex objects with an inner bean requires extra time, effort and maintenance as each object is nested inside another bean definition. In addition, since an inner bean is isolated from other beans in the context, sharing state between beans becomes very difficult or impossible if using multiple instances of the same inside-bean definitions.  Finally, tying together a set of tightly coupled objects with multiple layers of nesting can lead to confusion and difficulty debugging functionality that relies on those components. Although it can take additional effort to properly utilize inner beans during configuration, learning how to incorporate them into Spring MVC applications can provide significant benefits in terms of application complexity and extensibility in the future