According to the ANZ Research Team, “US policymakers are concerned about current disinflationary trends; the dollar may have a role to play in reversing that. If a weaker dollar helped to boost inflation, it would allow greater balance in US monetary policy settings i.e. the Fed could taper QE when appropriate for growth and not risk distortions in monetary policy impacting negatively via the asset bubble effect as they also watch inflation.”
With the exception of the euro, other countries have weakened their currencies recently, although they won't admit that overtly as it would be against the "spirit" of G20. That's more to do with smoothing frictionless international financial relations that anything else. Domestic inflation and growth take priority.