107% rule- be more aggressive in Q1?

Why wouldn't the leading teams be very aggressive in Q1 in order to reduce the number of cars on grid? In Malaysia, the eventual pole time was about...

Source: http://www.motorsportforums.com/forums/showthread.php?141902-107-rule-be-more-aggressive-in-Q1&goto=newpost

Pierluigi Aldrovanti Alejandro Aleman Eduardo Aleman Jaime Alguesuari