I think it's selfish not to. I'm also opposed to a similar issue of burying people in coffins. It takes up unnecessary space and it'd make more sense to fertilize the earth with our delicious bodies.
Wooden coffins slowly decompose too, and most coffins aren't air-tight, so the bodies also decompose reasonably rapidly. (Preservatives like Formaldehyde slow this down)
Over time they fertilise the earth too.
Graveyards, particularly old/ancient ones are rather good at growing grasses and plants and flowers because of this.
But I don't think I'd go so far as to say it's selfish to bury the dead.
There's little salvageable from a dead body, and vital organs tend to be the few things of use. Donating those is a useful and nice thing to do, in my opinion.
The rest of the body however, is of little physical use to others.
And since it holds a sentimental value for other people, it's fine to bury or inter the dead.
I personally would prefer to be cremated, but I can see that that's even worse in terms of helping others, since it requires fossil fuels (or rather, fossil fuels are used for it).
I watched a programme on TV recently debating the problems with dealing with human remains.
In Britain atleast there's actually starting to become a shortage of available spaces for graves, particularly in city graveyards. Building more graveyards may then use up valuable land otherwise used for agriculture or construction of housing/industry.
And the other alternative of Cremation, which came about in some way to counteract the lack of burial space, is damaging the planet through the burning of fossil fuels.
It doesn't leave many choices available.
There are other things to do, but some aren't quite as morally sound for some. Say, liquedising the deceased.
