Making Up The Rules as You Go Along

The FIA looks to make even stricter rules governing "flexible floors".  The unintended consequence of this is to cause teams to raise their car's height.  They would have to raise the cars to eliminate the possibility of undercarriage breaking from running over tall curbs.
The saga first hit the headlines after the Australian Grand Prix, when teams including Ferrari and BMW Sauber were accused of deliberately circumventing the rules to obtain a performance advantage.  The FIA's subsequent clarification affected the design of most Formula One teams' floors, sources said.  But Auto Motor und Sport contends that Ferrari and BMW's original floor designs passed even the stricter test; motivating the FIA to now quadruple the amount of load applied for the new Barcelona tests.  Toyota's Pascal Vasselon says,"Many teams will have to raise their cars quite a lot," he said, "but raising a car by) only a millimetre can mean two per cent less downforce."
If the FIA wants the cars to be run at a higher height, why don't they just mandate that?

Credit Yahoo F1 for the quote.