What a marvelous idea! Useful rather than wasteful. Cheaper rather than expensive. Ecological rather than affecting the earth forever. The body certainly won't care! So many people aren't aware that expensive funeral home caskets are often not required by law.
To me this isn't a "constant reminder" of impending death (hopefully many years out!) any more than my leather wingback recliner is a constant (negative connotation) reminder that I will be having shoulder replacement surgery soon and have to sleep in it for a while. Or that the ice scraper I have to keep moving in my car's console is a reminder that winter is coming sooner than I want it to.
Then again, I'm one who firmly believes that only I am responsible for the things I "think on"; that my brain doesn't just take over and worry about things like a dog with a new bone when I "remind" myself that only God is in control of my life.