Why use process.nextTick()?
This can create some bad situations because it allows you to 'starve' your I/O by making a recursive process.nextTick() calls, which prevents the event loop from reaching the poll phase.
There are two main reasons:
Allow users to handle errors, clean up any unneeded resources, or perhaps try the request again before the event loop continues.
At times it's necessary to allow a callback to run after the call stack has unwound but before the event loop continues.