I don't have too many issues with moulded plugs on devices that use less than 500 Watts, but above that and I'd rather not use them, as they can often fail due to the nature of the way they connect the wires to the pins in the plug, the worst culprits being washers and tumble dryers, get a bad connection in those and they can overheat and cause damage to the wiring in the plug, the socket and even the wall...
Though when it come to computer devices, I can't even keep a USB mouse working for more than a year without the wires breaking off inside the plug, I've got computer equipment from the 1990's that have moulded plugs, but they work flawlessly (then again, they were not made in a certain far eastern communistic country famed for poor-quality goods, cheap or not!!!), so it's definitely down to cheaper manufacturing techniques... :\
This picture below is a small example of what a moulded plug can do if it goes bad, if you have a socket like this, replace it, and if the copper wire behind it is discoloured with a blueish tinge, call in an electrician:
