Those in favor of forcing people to remain alive against their will often hypothesize that an institutional right to suicide would put vulnerable people at risk of being coerced or pressured into suicide.
There is no evidence for that position. On the other hand, in a society with an institutional right to comfortable, doctor-assisted suicide by barbiturates, it would be much more problematic for a killer to murder someone and make it look like a suicide. In such a society, why would anyone commit suicide by carbon monoxide poisoning or by gunshot? Some might choose other means of death, of course, but suicides by old-fashioned means would likely become somewhat rare and extremely suspicious, no longer the norm.
Some believe that a right to suicide would harm vulnerable people. But there's just as much reason to believe that a right to suicide would eliminate some incidences of the worst coercive deaths - murders.