WASHINGTON — The State of the Union just isn’t what it used to be. Sure, the pageantry and theatrics of the annual presidential address will all be there. The stem-winder of a speech from President Barack Obama. The standing ovations from his supporters and strategic smirks and scowls from his opponents. The wall-to-wall media coverage and cable news countdown clocks. But viewership is falling with 20 million fewer people watching last year’s State of the Union compared to Bill Clinton’s …