Because it is to align with the bare minimum FBD availability for launch. A compromise between Intel (worried about PR) and the OEMs.
BTW, I'm afraid your "Dempsey will beat Opteron in 2-socket systems" (in Q2) ain't gonna work out. Once again, you fall into the trap of comparing Dempsey against what AMD had 6 months ago, instead of what they'll have in Q2.
Does DDR2-800 / 1400MHz HT / 2.8GHz DC help jog your memory?
And you'd better pray that no virtualization benchmarks are run. Dempsey will be slaughtered.