I know...sounds completely backward...but doesn't it make some sense? A larger turbo makes more power at the same boost range because its efficiency is better in the upper RPMs and therefore the intake charge is denser/cooler -- right? And if a larger turbo means lower post compressor air temps, then the need for increased intercooling is reduced -- right?

If anything, it seems more important to have an effective intercooler with a small turbo that is cooking the air in the upper RPMs.

What am I missing?

bigger turbo, more air. stock intercooler would then become restrictive to the bigger turbo.
the boost would get trapped on the inlet side. creating backpressure, and in return making the turbo work harder to push the air through. kind of like a bigger fuel pump. you need bigger inj. to make use of the bigger pump. otherwise the fuel will just go back in the tank with smaller inj.