Toady, when you said before that non-fortress sites would be too big to reclaim, I'd assumed that they could theoretically span who knows how many of those 16x16 map sectors; but now that I notice the latest devlog saying they only go up to 17x17, I'm wondering... If non-fortress sites can't go far beyond the player limit of 16x16, why not limit them just one embark tile more (er, fewer?) and let sites use a common framework, suitable not only for eventually making other sites reclaimable but for eventually letting modders play as human towns, elf hamlets and such? At the moment I'm starting to suspect that the fact other sites can exceed 16x16, all the way up to the whopping one embark tile wider (yes, that's sarcasm) of 17x17, is not the real cause of their being nonplayable, but rather a technical means to enforce their nonplayability, while the real reason has been left unwritten (as far as I've seen), though it might be as simple as that the task of making all types of sites meet certain standards of playability is not worth your trouble in the near future (which I'd still rather hear than suspect while I hear other things). Or, is the intention to limit site sprawl at the present time, but leave room long-term to make sites that do stretch across a multiplicity of 16x16 sectors -- a sort of Dwarven/Elven/Goblin equivalent of Los Angeles, if you will?
A note to the mathematically inclined: I'm aware that going from 16x16 to 17x17 itself adds a grand total of 33 embark tiles, one more than the size of a fortress of maximum length and minimum width. I still think that whether you're looking at 16 vs 17 or at 16^2 (256) vs 17^2 (289) it's odd to let the size only just exceed what would allow a common site framework, if that isn't itself the point.
Also, if this has already been discussed elsewhere, say, in DF Talk, feel free to just point me to it.