While it's tragic that someone died due to their No-No Powder addiction, I'm not really keen on having the Gravemarkers in front of say, a dying sapling I'm trying to water, or something like that. Yes, we can press the W / Up / Enter key to bring up a menu so we can choose an object that's being overlapped, but I want to be able to click on that stone and have an option to hide it.
Something tells me even this won't stop a group of people committing mass suicide just to fill up an area with Gravemarkers, so why not also an option to hide all Gravemarkers altogether?