End of life Suffering

It could be just me but I recently heard of a very distinct group that opposes the use of Medical Marijuana for "end of life" patients. Now while I certainly respect every ones opinion and their right to it, really what is the difference with this type of treatment. When you have someone in constant pain and agony that is nearing the end of their time in our World why would you encourage that when there is an alternative. Relative to many other drugs they could be given that are not as effective and cost much, much more why not support the need these people have. If it can take the edge off so they can spend time communicating with loved ones and making plans why not allow them to live this way.