There is no constituency for reforming the executive. That is a simple political fact about the United States, and therefore no one with real influence is willing to follow the necessary implications of originalism for executive power. Why not? Because Americans want a strong president. They want a strong president to defend the United States from terrorists, to deliver humanitarian interventions, to respond to natural disasters like Katrina, to resolve financial crises, to combat climate change, to fix the deficit. The call for leadership by a strong executive in response to the crisis du jour is reflexive.
George W. Bush ran on an at least nominally "reform/weaken the executive" platform -- a "humble" foreign policy, restoring "honor" and "integrity" to a White House he portrayed as having run wild, etc. -- in 2000.
Barack H. Obama made executive overreach a central theme of his presidential campaign in 2008.
There's definitely a constituency for a less powerful executive sometimes, and that constituency can decisively influence the outcome of a presidential election.
When the crisis du jour is very recent and/or particularly horrific, it's probably easier to bring together the constituency for a strong/decisive executive. In 2004, Bush rode that theme to a second victory by invoking 9/11 and portraying John Kerry as the kind of guy who would consult the UN for permission before wiping the presidential ass.
But when the boogieman stuff has faded and aged a bit, and when the executive overreaches are easy to portray as either hubris (Bush/GOP 2008) or tactics to distract attention from jiggery-pokery or just plain pokery (Clinton/Dems 2000), the "maybe we shouldn't elect such pushy assholes" constituency can be mobilized.
Of course, Bush and Obama are also strong evidence for the notion that the "humble executive" crap generally goes out the window as soon as new boogiemen arrive on the scene.
So yeah, we're probably screwed.