Don't scare everybody off because it's not a best practice. If his/her server gets pwned they'll fix, learn, and move on.
A password is fine for your fun server. It's not super secure. It you're probably not interesting enough to get pwned using it.
I'm now on a fast enough connection with good enough hardware that if you were able to get into one of my desktops or even just the router I'd be inadvertently sending out a lot of spam or "donating" a lot of bandwidth to a DDoS.
Also, scans of the entire IPv4 internet take less than an hour now, so there's absolutely no security-through-obscurity.
[1]: http://krebsonsecurity.com/2015/01/lizard-stresser-runs-on-h...
[2]: https://blog.sucuri.net/2016/06/large-cctv-botnet-leveraged-...