in the long run we'll probably see some sort of safe burial to be done, by today or modders.
like a crematory workshop, making hashes that then are to be put into a coffin. zombie ashes are way less troublesome.
but, well, magma plus a better slab interface will do right now.
You seem to forget about ghosts. The main reason toady is making undeath more prevalent now is so that you don't have to be completely negligent to encounter it. Challenges seem less fulfilling if you have to go out of your way for them.
no, that's the point of slabs.
unless you talk of wandering ghosts, then those are a problem indeed, but for fortress/civ population a burial would prevent ghost and incineration would prevent zombie.
so right now magma+slab is a safe burial mechanism.
Except that if magma and slab was a "100% safe method of burial", then there
would be a 100% safe method of burial, and Toady just said there
won't be any 100% safed method of burial. Hence, magma and slab can no longer be safe.
Again, this can all be well and good to have some "random disaster" for players on one very specific condition - that the players are actually given a means to combat the problem.
Right now, you can flood your fortress with a careless river breach very easily, and while it's possible to prevent that disaster, there's almost no way to stop it once it has occurred, unless you went ahead and made failsafes you could activate (which is basically the same thing as preventing it, anyway).
You can prepare for a siege fairly well if you train up your military or build an effective deathtrap, but if your warriors are all dead or your deathtrap bypassed, pretty much all you can do is activate your entire civilian force as military, arm them with whatever's at hand, and hope for the best.
The game would be improved, in a sense, with a random event that you actually
could react to on-the-fly, rather than simply predicting it and preparing for it, or losing when it appears.
A game like SimCity lets you react to a disaster while it happens by hitting you unexpectedly (or just letting you launch disasters whenever you want if you feel destructive) get hit with a building fire or a plane crash or an earthquake or the like. The thing is, you don't have much way to completely prevent that, but you do have ways to combat it while it is in progress - you can control the spread of a fire with bulldozing, starve the fires to mitigate their damage, clean up the aftermath, and rebuild.
Here's the important part, though: Fires, plane crashes, tornadoes, and earthquakes all
STOP at some point. The amount of damage they can do, unless you specifically do nothing to stop the spread of a fire, is limited, and won't completely destroy your city.
A flood or breach of HFS or a siege that gets past your defenses keeps going until all your dwarves are dead - either you have negligible casualties, or a total fortress wipeout, with a very rare in-between state. Hence, "disasters" in DF are either "meh, another siege, Urist, pull the Boatmurdered lever", or else "Everybody's Dead, Dave".
It's because of this I say that having ghosts that you can't prevent is all well and good
if and only if there is some sort of means of "defeating" them once they are created. Maybe that means appeasing them by throwing lots of expensive crap on their slab as an offering, or maybe that means that dwarves get priests and exorcists that can do spiritual combat with ghosts, or maybe that just plain means that you can "kill" a ghost with a sword, but as long as we have some sort of way of actually making the event
stop at some point, then it's all good, and maybe the game can start giving you some sort of "challenge" that doesn't come in the form of a total pass/fail "did you remember to do X" type of question.
If, however, ghosts spawn, and there is no way to stop them from killing your dwarves and slabs and such don't work, and you can't stop or combat them in any way, then we're dealing with the equivalent of playing Sim City where the earthquake just never stops. There's no chance to rebuild or manage the disaster, because the disaster never stops, and any means you might take to mitigate the damage are ruined as the disaster just continues to break through your preparations and actions.
One of these makes for a good game, and one of these makes for a bad game.