When using an asychronous command, e.g. & from dired-mode, it would be nice if it didn't pop up the buffer until output was received. Often, no output is received, for example, when using an asynchronous command to start an external viewer (here, it makes sense to start it asynchronously, as the user doesn't want Emacs to block until the viewer exits).
This thread:
https://groups.google.com/forum/#!topic/gnu.emacs.help/xrs6ny67c_4 discusses the issue, and gives some workarounds and partial solutions; but would there be any disadvantage to changing the behavior to pop up the buffer when input arrives, and otherwise not do so?