Best AI?

[Ludens]

It's hard (but not impossible) to imagine them skimping on the feature they touted so proudly in S:TW -- an engine inspired by Sun Tzu! -- when most everything else going from S:TW to R:TW was a major revamp.

I agree, but really, if you study the way the R:TW A.I. responds and compare it with the way the M:TW A.I. does things under similar conditions, you cannot but conclude that something has gone very wrong. Off course, because CA completely redid the R:TW engine, they probably had to rewrite the A.I. as well. Game A.I. doesn't necessarily work like the human player: its interface is highly dependent on the engine itself.

I think they wanted to make it more accessible. Especially since they included ways to trick the AI ('loose formation' units looking more numerous, for example) piling the natural AI disadvantage with extra, purposely-programmed "stupidity".

The S:TW engine didn't have such debilitating nuances, so I still posit that it had a simpler task overall.

I rather doubt that was implemented. A more important factor would have been that more CPU power was allocated to the graphics. Also the increased speed of movement and battle resolution in vanilla R:TW would have left the CPU with even fewer CPU cycles to formulate tactics. If the S:TW A.I. responded a bit sluggishly, you probably wouldn't notice and it wouldn't matter much because battle resolution is slower and quick strikes count for less. In vanilla R:TW quick strikes are all-important, however.