Relying on Russia's Crew Launch Vehicle stops us from being able to apply enough of pressure on Russia to keep them strategically in check. Russia's recent actions on Syria, Iran, LGBT, and now Ukraine needs response from a strong U.S. which isn't option due to the reliance that we have on their Space Agency.
We need to either bring the Space Shuttles out of retirement or partner with SpaceX to deliver a crew capable vehicle in as little as a year.