FWIW, PVE newbs always get slapped by this. Most don’t get completely erased – although I’ve seen people come here to the forums and say something along the lines of “WTF, I was gone for a month and now everything is gone” – but the vast majority of newbs lose at least one wheel or pen because they don’t know about decay and claim mechanics.
The game should have journey steps and/or additional lore to help teach players about claim, decay, and stability. A few loading screen hints aren’t enough, because:
- they’re random, so you might not get to see the ones that matter
- people tend to stop reading them after a while, especially after they start repeating or after they see a joke like “don’t eat yellow snow”
- they tend to be too short to fit a proper explanation about stuff like claim, decay, and stability
- even if you pay attention to each one, there are people whose hardware is fast enough that they won’t be able to read a long one before the loading screen is gone
Sorry for the somewhat off-topic rant here, but it’s a pet peeve of mine.
Or make sure to teach the players what’s going to happen. If you know how the game works, then you can prepare, whether it’s PVP or PVE.
On PVE side, if you’re solo – no clanmates – and you stay away for more than a week, you’ve lost everything. Your inventory is going to be a drop in the ocean compared to all the other stuff you’ll have lost.
If you do have clanmates, then you don’t have to lose anything at all (barring bugs): put your inventory in a chest, log out, and let your clanmates refresh everything.
Um, unless Funcom did something extremely clever that I haven’t noticed, the bodies do stay on the server forever. They’re just not rendered. If official servers aren’t already crashing due to an accumulation of all the players who stopped playing over the course of 4 years, then I don’t see why they should start crashing due to a change that would mostly affect the client. 
Honestly, I think that auto-killing would be okay, but if players don’t want that, it would still be better to have auto-hidden bodies respawn (with their inventory intact) at a newbie spawn when they come back.
As I’ve already pointed out, respawning them where they logged out can wreak havoc on someone unsuspecting on a PVP server, someone who built a base on top of what seemed like a perfectly empty spot only to find their stuff missing when a body-vaulted toon logged back in.
On PVE, this can be equally frustrating, but this time it’s for the person who came back: they’re suddenly trapped in someone else’s base and if that someone else is offline, there’s nothing they can do except suicide their toon and lose all their stuff.