Biplanes went out when it was found you could get the same gains by making a single wing thicker which lead to a simpler design with room for the undercarriage, fuel and weapons etc.
There is a case for tandem wings, of various designs such as the LM design, for larger aircraft; but they tend to make the platform more stable, which isn't design feature you want in a fighter.
The compromise in the fighter world is the canard combined with relaxed stability, which is what you have in the Typhoon.