Given that Volcanic sources arn't really going to be safe forever (or stable)... Id say that would be your own fault and you should have kept a backup.
What do you mean by that? Magma forges are fairly safe and reliable if they're used carefully; I haven't heard any plans or suggestions to dramatically alter that.
One goal of the game is to have even inhospitable areas at least marginally survivable. That means that magma forges should at least have the
potential to replace wood forges completely. I could understand, perhaps, if you feel they should a bit less perfectly safe or less totally better than wood forges; but what you're saying is "You only used a magma forge? You suck, you fail, you deserve to lose. Stop
cheating so much by only using a magma forge," which seems... extreme.
Magma forges are a valid alternative to wood forges. I don't see any particular reason, logically, why players should be forced to have wood forges... if a player wants to focus solely on magma forges, I can't see why you're so dead-set on preventing them from doing so.
It is also quite unintuitive to new players to have it work in the way that was suggested. Why shouldn't a moody dwarf use a fully-functioning magma forge? Why would they just stand there doing nothing? How could player who hasn't read the wiki know that they need a wood-burning forge because magma-forges are, inexplicably, no good for moods?
It just seems like a bad idea.