Grave Goods or Grave Bads

I'm not sure what it is about the idea of grave goods but it seems rather silly and illogical to bury anything with the dead. Oh I am greatful that various cultures, both past and present, have buried goods along with their dead otherwise Archaeologist might not have a lot to do. I am also fully aware that there are number of reasons both religious and status based as why people include goods in graves, but it still makes little sense to me.
Take for example a sword. On average a basic, battle ready sword will take a month or two to forge. For a good quality sword that will last more then a couple of battles your looking at six months to a year. There is a lot of time and effort that is put into forging a sword and yet they get buried with the dead, who lets be fair, in a nonreligious sense do not need them. Swords are also expensive and many warriors who could actually afford a sword, let along learn to use one (very complicated weapons to use well), would probably be appalled to know that their trusty (or thrusty) sword was then placed in a hole to rust. It makes more sense to me to instead give your sword to a relative, say your son, so that he can continue using the sword. I know I would probably remember the person who gave me a sword for a longer time then the selfish old goat who took his sword to the grave.
This waste in the form or grave goods is also present not just in weapons, but also in food, materials, and other tools. What does it matter if you bury sixty pounds of gold with your dead when some theif years later will just dig it up and run off with it anyways. The gold would be better spent on the family you leave behind after your dead. But some could argue that gold and swords are just things and have no real value and are therefore estentially worthless. However the same argument cannot be used when it comes to food. Food has worth as it can mean the difference between life and death. If one were to look at the South Fore of Papua New Guinea and there endocannibalistic mortuary practices, you would see that not only do they honour their dead through eatting them, but also recycle them as a source of protien.
In our own western culture grave goods are rare dependant on the burial practice followed. Most graves may not include any items, though grave gifts may be incorperated in some way. Flowers, cards, teddy bears, flags, or even beer can be thrown on top of the grave in respect to the dead. This inclusion of gifts therefore gives me a new idea. Maybe these goods buried with the dead that we keep digging up aren't possestions of the dead at all but gifts from mourners. Which would therefore, at least to me, would insinuate that there exists some form of grave gifting compition. Estentially you would have those seen as wealth competeing with each other over who can throw the most wealth into a grave and therefore who respects the dead the most.
This idea of competing to show respect seems absurd, but then so does the act of wasting goods on the dead.