As a country we need to be able to have responsible, sober debates and actually vote through policies instead of just working through whoever happens to be in the Oval Office. It's an unstable way to do things.
That said I would argue it's mostly unstable because the Republican party has been hijacked by its extreme right wing. It's astonishing to see that even with control of both houses they can't internally agree on policy enough to get things done. Much less find some sort of bipartisan compromise/consensus. Dems have their problems too, but I think the bulk of the responsibility lies on the very hard right impulses of the likes of the Freedom Caucus and the Ted Cruzes of this world.