If that's the case, why didn't we attack the people from Syria, or Lebanon,
or
Jordan, or Saudi Arabia, or Egypt, or Lybia?

Because our leadership is just smart enough not to. Not that they wouldn't
/want/ to, they just know that they'd have the US population up in arms if they
went that far off the deep end.

Since when do Americans go to war with
someone because they look like somebody who did something nasty to us?

How many Afganis attacked us before we deployed B-52s? Granted, its a cesspool
over there, but it wasn't 'our' cesspool, nor did people from Afganistan take
part in the 9/11 attacks. If we struck back at only the groups that nailed us,
Saudi Arabia would be under new management right now. So instead, we went
after a country filled with people who looked quite a bit like the folks that
zapped us, after claiming they were a genuine, immediate threat to our internal
safety.

When did
we become so stupid?

Sometime around when we sent bombers to drop on downtown Belgrade.