You don't absolutely need to know what your opponent is doing, all this emphasis on early scouting, etc, is sensible but too 'safe'.
For instance Jaedong (best zerg in the world) frequently fast expands without scouting, or even, gasps, 3 hatch before pool.
IM humble opinion in the current stage of your evolution as a player, you should practice with always fast expanding (choose bigger maps), regardless of scouting. You'll probably find yourself in a large economic advantage in 70% of your games. Because seriously, if a zerg only expands when he sees a terran expanding, THAT IS TOO LATE.
I wrote some pretty ranty comments that everyone should check out. In conclusion, people should listen to those who actually play the game at a high level rather than pay attention to the vote counts. Because in the end... an aggregate silver league opinion... is still a silver league opinion.
You can see on the TL wiki that FE counters 1 base play.
Two years later I think I'm obviously right.