More importantly: if the tested drug can't beat olive oil on the very thing that the drug is meant to treat, then why should it be approved at all?
(Drugs should be tested against the best existing alternative treatment, not merely a placebo. We are not interested in whether a new drug has a non-zero effect - but whether it is an improvement on the state of the art in some way.)
It might be an improvement on the state of the art in some other way. For example, a new antibiotic might be less effective than existing antibiotics, but have no cross-resistance with them and therefore be useful in treating antibiotic-resistant strains in the future (the magainin case), or a new antipsychotic might be less effective than existing antipsychotics for average patients, but more effective or less damaging for a few. Finally, you might be able to get synergistic effects by combining the drug with the best existing alternative treatment.
(Drugs should be tested against the best existing alternative treatment, not merely a placebo. We are not interested in whether a new drug has a non-zero effect - but whether it is an improvement on the state of the art in some way.)