Speaking as an American, I'm terrified of the "massive changes" that would be required to "fix" (replace, really) the Constitution. It could mean civil war or the disintegration of the nation into a bunch of probably-warring nation-states.
Moreover, I'm not convinced our current problems are purely local. Trump followed on the heels of Brexit, and right-wing nationalist/populist movements are on the rise across Europe. The world is going through some weird changes right now, an angry reaction to future shock, and recent US politics are just a symptom.
I call it "the state rewrite problem", which consists of two assumptions: one, that the quality of any constitutional framework degrades over time as political actors adapt to it over generations (except maybe if the constitutional framework was particularly bad from the start) and two, that any rewrite/reboot intended to counteract that degradation would be even worse than that if the established set of political actors is involved. This traditionally is only ever avoided in the aftermath of some particularly violent crisis. Now the art would be to avoid that crisis.
Drafting random collaborators for a rewrite could be one approach, but they would still be prone to getting influenced by the establishment. Maybe dozens of randomized committees working in parallel, with all but one draft discarded at random, to make sure that writing happens out of the spotlight, and with little incentive for self-serving elements?
Moreover, I'm not convinced our current problems are purely local. Trump followed on the heels of Brexit, and right-wing nationalist/populist movements are on the rise across Europe. The world is going through some weird changes right now, an angry reaction to future shock, and recent US politics are just a symptom.