Why can't our war heroes win the Presidency anymore?

Any idea why, in nearly the last 20 years, are we as a nation shunning our war heroes for president? Clinton (draft dodger) beat both George HW Bush (war hero) and Bob Dole (war hero). GW Bush (protecting Texas from the Vietnamese) beat both Al Gore (war photographer) and John Kerry (war hero). And now, Obama has a huge lead on McCain (POW). What gives?