How many times have you downloaded a product to find that it comes prepackaged with products freely downloadable? You would quite often see Apache web-servers or a Java runtime bundled with a product. These are typically either open sourced products or are under a license and customized. Custom is good. And I have an evidence on the upper left. It gives products flexibility to make it work as per your requirements. Off the shelf or cookie cutters are good as well but may not be suitable for all the needs. This is quite true with Application servers that are built on top of products like Apache or Orion. A bunch of custom web server plugins and custom protocols and now I can make money on top of these freebies. JRE is another but not usually highly customized. JREs are pre-bundled to avoid having to download one or due to certification issues or a need of a specific version. I went custom too. Very recently while working for a Client I came across a .NET security issue that required DLLs to be colocated with the invoking application. It was a Java application that invokes some C# APIs. Packaging is important. Now, it was needed that the dll coexists where java.exe was. A good scenario to go custom. Many installers like Install4J provide a flexibility to bundle a JRE with the product. I am not promoting install4j as this not being an open and free product but you got my point. If I can have my own instance of JRE then I can also copy the dynamic libraries in it that the application uses. And your custom JRE is ready to be ridden.