You've been able to have food less fortresses for a very long time: neither vampires nor necros need to eat, and gobbos don't either, and they became possible citizens with the introduction of visitors and petitions.
The new experiments were definitely a shock when they attacked the first time, but it's something that can be countered by adjusting your game play (or, in my case, fortress design).
The inevitable zombie apocalypse is an issue Toady has acknowledged, but had to put aside due to the Premium deadline, so hopefully there will be some adjustments. One of the adjustments ought to be that intelligent undead should be treated at least as badly as necros, in my view.
I have less trouble with the new undead than I have with the completely unbalanced Villains, however (I know they're supposed to be adjusted, but Toady's comments on the issue do not inspire confidence). Currently there is no defense against Villains whatsoever, apart from completely keeping all visitors out (caravans might be safe, and possibly diplomats as well [from a villainy point of view: they can still go bonkers]). At best you can get some confessions out of some and imprison or beat them, which does absolutely nothing to deter them or even to get your artifacts back, even if they carry them. It's basically an endless whack-a-mole game where you can do nothing to prepare, and the number of villains is effectively unlimited.
Once magic is introduced properly (in 5+ years or so, after the Big Wait), the intention is to have a magic adjustment slider of some sort, so you could have completely mundane worlds (no dwarves or clowns, all religion being completely fictitious), to heavily magic worlds, with a range of settings in between. What sliders there will be remains to be seen, but I could definitely see the possibility of both strength, commonality, and attitude towards magic being adjustable. The general kind of magic present would probably be controlled by a bleakness slider rather than a purely magic oriented one. Also, you're supposed to be able to adjust the myth part, which ought to allow you to nudge the world in various directions.