The Supreme Court did not dismiss sentencing standards.
Sure did, Federal guideline standards were struck down. What we are seeing here is a 'trickle down' effect. Judges don't have to go by legislative standards if they don't feel like it anymore.
The Supreme Court in U.S. v. Booker, relying on Apprendi v. New Jersey and Blakey v. Washington, struck down the mandatory requirements of the Federal Sentencing Guidelines. They severed the unconstitutional parts from the rest of the guidelines and specifically did not strike down the Guidelines themselves. The first cases deal with state sentencing guidelines. These decisions apply to the states and the Federal government. See: http://supct.law.cornell.edu/supct/html/04-104.ZS.html