On the contrary in 2013 the kind of person who builds their own PC's is the only one who likely cares about technical specs. If "good enough" is good enough for you there is very little reason to build your own box these days.
I exclusively use server or workstation/server class motherboards from Supermicro or Tyan not just for myself but also for my parents, so I can then largely ignore the hardware for 5+ years plus not worry about non-reproducible errors from radiation flipping a DRAM bit. I've done this since 1995-6 and never had one fail in the field except through an act of God (http://en.wikipedia.org/wiki/2011_Joplin_tornado).
For this purpose, decreasing stress from thermal cycling is good.
(Yeah, they're grossly overpowered for what my parents do, but since I'm not including my labor in the cost they really don't cost that much.)
I've used ECC in every one of my machines for the last decade or so - except for the very last once since it's was impossible to get without spending a crazy amount of money (xeon processor).
And as mentioned elsewhere, AMD's consumer CPUs support ECC if the motherboard enables it.
Low power consumption is not one of the specs the PC building crowd really cares about. Especially if it means taking a performance hit.
Hell, many are proud of their beefy 1kW+ power supplies and the ridiculous power load they draw.
Others are proud of their energy-destroying bit-coin mining setups.
You certainly can't assume that the home builder cares at all about power consumption.
I'd be proud of my bitcoin mining setup too if it could violate the laws of thermodynamics.
I build most of my desktops, and I certainly want to reduce power usage when I'm not using them. Enough so that I'd pay for a power supply that supports the lower power states.
Not everybody who builds their own PC is doing so to make a ridiculously over powered system.
My actual, active goal is to build a quad core machine with 16 gibibytes of RAM that can draw < 100W at full bore.
IOW, you can't assume that those of us who build our machines are all, "Look how big my electric bill is!" wastrels, either.
TDP is all about cooling capacity and PSU capabilities. If you're worried about saving energy, get the processor that will run at the highest speed while computing so that it can get back into power-saving mode sooner. And you can always under-clock the standard desktop CPUs if you really want to - a 3770 can be configured to behave pretty much like a 3770T by tweaking the base and Turbo multipliers.