About a month ago I blew £700 on one of
these. It was a pretty compelling "rip off" given that I'd have struggled to have built a machine of that spec for the price, and the situation will likely be the same in X years time when I need to upgrade.
Admittedly I'm not a huge fan of the non-standard motherboard, but IMO this ceases to be relevant to anyone but the most spec-hungry, latest-tech-chasing enthusiast; given that by the time the average user comes to upgrade their home built system the only things that won't be obsolete will be the case and PSU anyway.
And as regards disposibility and warranty claims, my previous Dell took a beating for 7yrs, had several upgrades and the only hardware failure it suffered was a knackered CRT monitor after about 4yrs.
I'm all for sustainability and making things last, but in this case I don't think much comes close to Dell for out and out value.