I was going to say much as Findulidas did.
It's a single-player game. You can make (and break) your own rules. Don't like a particular wild animal (or enemy sentient?) being so tough? Edit the raws. Decide that your fort is not going to use anything other than copper armour? Then just don't make anything other than copper armour (and forbid/dump/sell/melt or just plain ignore everything else that falls into your lap). Saying that you defeated the mightiest beasts when you just disabled them with the aforementioned trick, or announcing that you were a copper-only army while you did not stick to the letter of the latter is of course misrepresenting yourself, but insofar as the game you're playing is concerned, you can't fool yourself and that's the main person that counts.
I could make my dwarves able to swim in magma (but I don't) or have a reaction to create spoilermetal from dacite (again, I don't), and I don't have to construct my massive fractionally-completed apartment-building purely out of marble blocks, properly made and with with no reaction cheats at all (and, yet, I am doing[1], and have massive quantities of marble blocks still to use, and plenty more on the way, but I actually haven't added them all up to see if I need a new quarry opening.
It's probably "exploity" that I eschew the "T"ravel key (except for map checking, coming straight back ">"-out to where I just was, without moving) and Sneak-travel absolutely everywhere. Even when I'm on 2567/3900 Ambusher skill (when there's no more practical gain in sneak-speed and all I'm doing is avoiding all combats I'm not actually seeking, even if it means taking a detour around a herd of elephants so that they don't notice me and alert the dingoes...)
So... well, good catch. That's a mode of play that's possible and some people will not deliberately seek that out (perhaps if they're fed up of Danger Rooms, or whatever they currently do), while others may will now play differently to avoid 'accidentally' doing such a thing.
[1] And I'd have built more of it by now if the stupid dwarves weren't insisting on standing on the two (non-adjacent) spots they're building their own walls on, and suspending the job because a "Creature is occupying the space"... themselves! I've made sure they've got adjacent places to stand, and on this particular level (about four up of about a dozen) I've succeeded in filling other gaps by just persevering and cancelling/redoing the job as soon as I notice that the currently tasked dwarf is standing on the tile his "nearly completed" construction is being made on, cancelling and re-establishing it, but these two spots (one on the southern wall and one on the northern wall) are just not building... Argh! Anyway, gripe over... Just saying.