1. Mathis is Bond's best friend in the novels. Likewise, Felix was never married nor widowed as in LTK. They chose to take the character in a different direction. I'm sure he'd have gone on to be a friend of Bond's, but the relationship dynamic was different than that of the novels from the beginning.Setting aside the fact that Mathis shouldn't have died as he is still alive in the novels, Bond's treatment of Mathis' body is very out of character.
Mathis, along with Tanner and Leiter, is one of Bond's best friends. He would never callously and cold-heartedly treat his friend's body that way, particularly when it serves no purpose for him to do so. See Dr. No and Quarrel. Quarrel is just killed. Does Bond just walk away? No, he turns to pay his respects to the body only to nearly get his foot shot off before being forced to walk away. In From Russia With Love, he squeezes the dead Kerim Bey's shoulder. In the novels, he is greatly affected and upset when his friends and allies are killed, but he manages to push those feelings quickly aside to get on with his duty. He doesn't toss his friends in dumpsters. Additionally, I don't think Bond would just sit with his dying friend and do nothing. He would have put him in the back of the SUV and driven like hell to the hospital whether he was likely to get there in time to save Mathis or not.
In addition, putting Mathis in the dumpster makes absolutely no sense. If it's to hide the body, he failed. You can see the dead motorcycle cops in the background in one shot and Mathis' arm ends up draped over the edge of the dumpster. Why couldn't Bond have just left Mathis in the road or propped him up against the dumpster? I understand him taking the money but not the rest of it. The whole scene didn't work for me.
2. You're acting like Bond showed no love for the guy whatsoever. He cradled Mathis in his arms and provided him a few peaceful moments with the last friend he had. After Mathis died, Bond continued to hold him and fight back his emotions (props to Craig for pulling that off so well). It then skips to a few moments later when Bond leaves him in the dumpster (which is still better than just leaving him on the street, IMO). Totally in the vein of how Bond treated Quarrel and Kerim in death, IMO. And it wisely left out the unnecessary sentimentality. The celluloid characters weren't quite as chummy as their literary counterparts.
3. As in DN and FRWL (and the LALD novel), Bond took the time and effort to avenge his friend's death.
4. I miss the literary Mathis, too; However, I'm glad they gave him this honorable a treatment, rather than what they did with the Felix character for years.