It's easy to blame victims, but even EA broke a massive amount of XBox 360s, between 30-50%, tenfold at the time Microsoft claimed failure rates to be between 3-5% a long time ago. They have hundreds of units, so not a bad indication.
I believe when games start to push the 360 harder, the GPUs will get hotter and thus more people may experience failures. The solder melds and motherboard flexes causing disconnect, refurbs will probably be less reliable as the solder after heating will be more prone to repeat failings. IMO Microsoft should provide consumers with a more sturdy product and not replace broken units with refurbs, but with a brand new sturdy product.