The point is what other node would they use? You keep saying they waited 2 years and shipped on 90nm. What else would they do? MS ship xb360 a year earlier in 2004? ??
MS had to dump xbox asap, and try to catch Sony off guard with xb360. This forced Sony's hand.
The process node available was 90nm. 65nm, the next smallest node, was not ready for launch in 2005 and the rollout for it was slow as we saw HP scheduled to start 2006 and SOI only scheduled to appear in 2007.
Sony couldn't depend on such a slow adaption and so were forced to produce on the same node and the rest is history.
Let's contrast to the here and now...
28nm is shipping now.
Nextgen machines aren't expected until next year. A full 12 months after the first run of the full gamut of 28nm. Not just low power as the case was at the end of 2005 65nm.
In other words, this go around, there is a real possibility to ship on 28nm in 2012.