I can't imagine any 2 pin plug being as mechanically stable as a 3 pin. Certainly here in Asia I am regularly being driven bonkers by 2 pin plugs dropping out of sockets the moment a butterfly shakes its wings on the other side of the planet.

One common complaint I get from my newly arrived expat colleagues is that their PC gives them slight electric shocks when they use it. IANAE (I am not an electrician), but I assume that this is because of some capacitor voodoo in the PC's power supply. The problem is cured by grounding the assembly.

The British plug/socket embodies the British ethos: nanny state, 'cannot be too careful' etc. In British parlance it is 'belt and braces'. But yes I agree it may be overkill.