It's apparently hard to program a good enemy AI into a simple game...
It's not that you can't get something that will exhibit smart behaviors, it's just that testing will reveal... special behaviors, by which I mean, inadequate programming causes the AI to be unable to cope with some situations.
Such as... the player hiding. (In the below videos, the hyperactive orange and red character is SA-X, a sort-of evil sort-of clone of Samus Aran from the Metroid games. The other similar-looking character is Samus, the player character, who can turn into a ball to move through tight spaces.)
Some people remark that the music (which is the theme for the SA-X) sounds a bit sarcastic. I'd tend to agree.