Well, as a psychiatrist, I have much more interest and training in psychotherapy than is typical, and I really want society to move away from the drug-fix standard. However, I will say that those disclaimers are often not truly attributable to the medication. Companies are required to report that drugs may cause any of the adverse events that occur during the trial, whether it is clear that the drug caused it or not. If you take a bunch of mentally ill people as your study population, invariably someone will become suicidal. That does not mean the drug itself caused it. However, serious life-threatening adverse events are things that the FDA often requires advertisers to disclose anyway. That said, there are some cases where some drugs may be associated with increased suicidality, at least in certain populations.
One good case example is the controversial FDA warning that has been applied to all antidepressants for teens and young adults surrounding suicidality. Whether that association is actually valid (or at least for more than a couple specific meds) is controversial enough, but the result of this warning is that teens and young adults presenting to doctors with depression are much more often receiving no treatment of any kind, including therapy. The suicide rate has seen a significant increase. While causality is extremely difficult to demonstrate, I find it very clear that no treatment for depression is far worse than an SSRI even if it increases suicidality compared to placebo. Best is therapy or therapy + SSRI for that population which, for even those where an association is possible, combination with therapy eliminated risk conferred by the medicine.
Back to the topic at hand. I do think, obviously, that mental health / deranged mental states are of paramount importance in commission of these acts. However, I think the problem relates much more to how society treats these individuals than how the mental health system does.