To expand on what greenlydia said, in my opinion, medication is most important when the user isn't able to be receptive to therapy because of the distractions caused by their particular problems. Medication is most useful in masking the symptoms while the user is starting in their particular therapy.
While there are people with a purely biologically-based mood or anxiety disorder that can be treated fully by SSRI's and other mood-altering medication, it seems rare to find a person with this problem who doesn't benefit from some sort of counseling or psychological-based therapy. Biologically-based mood disorders are most often related to endocrine function, from what I understand, and SSRI's aren't called for in most of those cases- other medication targets the specific problem.
I have nothing against the use of medications, but medications ALONE are, in my humble opinion, a dead end. They simply mask the symptoms while the root cause of your anxiety and depression continues to fester.
Many people can manage very well with therapy alone. But for those who can't, then a combination of therapy and medication is very beneficial.
As in all things, we are all different. Everyone must find the approach that works for them. There is no such thing as a one size fits all approach.