I've played a few games with "frequent" extreme planets, and the AI never seems to research the extreme technologies. I started at normal difficulty/intelligence, and I've increased a few levels, still with no results.
In my current game, I'm three years into a large universe on "tough" difficulty. I own around 90% of the planets because I'm the only one who researched any of the extreme techs.
As a result, I'm #1 in all categories despite significant underutilization of my worlds - most planets are less than half full, and only at 11 or 14 max population. I simply don't need to, because I have ~280 planets plus another 20+ colony ships still on the way while the other races combined have fewer than 30 planets (and losing, thanks to influence).
I'm nearly out of stuff to research - I researched the full missle path in four weeks (I do have very fast research) and the missle defense path in only three.
What gives? Am I missing something (or is the AI)?