Yes, I agree. But the issue is not whether God can resurrect us if our bodies are destroyed by fire (or anything else), but whether or not cremation - under normal, non-emergency situations - is an appropriate way for Christians to handle the remains of those "who have fallen asleep" in anticipation of the resurrection.
I don't think it sends the best message/testimony to others, although I would not dare to tell others how to live their lives or respectfully handle the remains of their loved ones.
I think something that has been missing from this conversation is the nature of cremation practices. It is not just burning the body until the flesh is consumed by fire, but it is also the grinding up of the skeletal remains into a coarse powder. If it were just fire, that's not that much different than letting the body decompose. But the grinding down of the hard parts of the body (bones, cartilage, etc.) into powder is the destruction part of the process.
Does that tell the story of resurrection and future life in the body, or does that paint the picture of final and ultimate destruction?