Yeah I'd say the opposite, keep it plugged in for earthing.
The risk of shock isn't much (although you'll still know about it

), since the purpose of the PSU is to step down the voltage, it's not very dangerous, I'm more worried about static than getting a shock off anything. Also, the connectors mostly have pins well out of the way of where you will touch them, PSU molex connectors for example, you can safely touch the connector even if the main system power is on, I hot swap case fans if I need to replace/add/remove them....probably not advisable from a hardware point of view but as it's an always on server I don't have much choice.