No, federal courts should not have more discretion over the sentencing of criminal defendants, because most of the laws that are enforced are state laws. If a person violates a state law, they have to answer to a state court. It would be too much big government to allow the federal government to determine these sentences.
Federal courts should have more latitude with regards to sentencing of criminals, especially with non-violent offenders. Drug crimes are especially poignant because enforcement of marijuana laws has been relaxed by the Department of Justice. The criminal justice system is already backlogged with cases and any easement saves time and money in the long run.
While I generally believe local and state courts are the most appropriate judges on sentencing questions, the United States has unfortunately drifted into a pattern of over-sentencing. Since local and state judges are more susceptible to public opinion, it is necessary for federal judges to take on more responsibility, discretion and oversight to ensure that we do not imprison more people, for longer periods than necessary.
I do not believe federal courts should have more discretion over the sentencing of criminal defendants. We have guidelines set out for a reason and they should be followed. The only reason those guidelines exist is the fact that there was a problem in the past. Assuming that the problem has disappeared is dangerous.