I do not think it's practical to completely disarm at this time. The security dilemma would have to be resolved before that could happen, and we simply don't have that level of trust between nations yet. However, it would be a show of good faith to reduce the arsenal. No single country needs enough nuclear weapons to incinerate every square inch of planet earth four times over. It is irresponsible and impractical to possess so many weapons of mass destruction.
Despite the warhawks in politics, war in the world is on the decline. Complex interdependence is increasing. Yes, there are major inequities that still remain unaddressed, but at least we aren't at each other's throats as much as we used to be. There are some regions that still need stability and that may or may not require intervention, but on the whole the world is much better off than the days of the Cold War. Don't you agree?