Glad I came up with it ooh slightly more then 2 yeas ago.
I'd like to thank Takeda_Shinukage for helping to keep the thread alive and at the top of the aging-and-dying sub-forums which I think contributed to it being noticed by the devs. I'd also like for folks to note the difference in positive/negative response ratios the exact same thing gets when a dev says it, community objectivity could stand for an upgrade.
Now to clear up a few misconceptions.
No one is proposing that a body at sea has to fast-travel at any time. Ocean currents by definition move slower then boats. Sea-creatures carrying a body might be marginally faster then a boat but your not in control of which direction you go. So no one can ever get anywhere faster then by staying in their boat and rowing.
Personally I favor maximizing the 'castaway' scenario and to that end an instanced island separate from the normal map would be something to look into. The map generation for a small island every time someone drowns is likely prohibitive, so a portfolio of a hundred or so could simply be used with each individual (or small group if they drowned together) placed onto a randomly picked one. If folks ever start to learn the islands, just rotate newly generated islands into the portfolio and old ones out.
This Instanced island system has many benefits, such as..
1) Eliminating any chance of a return to the mainland which might make for a very easy (you end up in a place you know) or very hard (you end up in enemy territory) experience. Instead the post death-at-sea can be far more consistent in challenge or scaled in a appropriate way, such as the farther out to sea one was when drowning the harsher the island given.
2) Ensures that the castaway/s are and remain alone. Any permanent island (which I absolutely want to see in the world) will eventually be discovered (and I think we want to avoid drowning as a means of discovering them) and eventually inhabited and very likely have ships visiting it regularly. This would greatly debase the cast-away experience if one can simply hitch an immediate ride back home. Likewise being in an off-map instance would block anyone from launching a rescue operation to pick you up.
3) Forced self-rescue. With no outside assistance coming the cast-away individual must go through a mid to long duration survival game on limited local resources, on minimal tools in unfamiliar terrain and build from that situation a means of escaping the instanced environment (moving away from the island in a raft being the most obvious, but other options might exist). At the moment of escape the can be returned to the normal map at the exact location of the original drowning, (or even a point even further from land), again further eliminating any concern over fast-travel.
Once back on the map they are not out of trouble though, further challenges and even repeat deaths and island instances could result (this was actually fairly common in a real cast-away scenarios, escaping one island to end up on another). But the central idea is that the player would be actively involved in this struggle at all times, with their fate very much in their own hands.