> This is not a matter of opinion. Always clean up after yourself, the kernel doesn't know shit about your application or what state it's in, you can not rely on it to cleanly terminate your process.
If you have an open file or network connection, the kernel is guaranteed to close it for you when the process is killed (assuming it hasn't passed the fd/socket to a subprocess, etc). That's not a matter of opinion.
Yes, if you are writing to a file, it is possible abruptly killing the writer may leave the file in an inconsistent state. But maybe you know your process doesn't write to any files (that's true in my case). Or maybe it does write to files, but you already have other mechanisms to recover their integrity in this scenario (since file writing processes can potentially die at any time–kernel panic, power loss, intermittent crash bug, etc)
