It will need to be compatible with any changes made for the standard frontend, it will need servers to run it, the code can't forever keep running on Java 1.2 o

It will need to be compatible with any changes made for the standard frontend, it will need servers to run it, the code can't forever keep running on Java 1.2 or PHP 4.2 or whatever, you will need to retain expertise on it all, etc. etc. Maintaining these things, even without user-visible changes, can actually be quite time-consuming and difficult.