This is a forum for suggestions on how to improve the game by changing how the game works or by adding new stuff.
I get the impression that 1x1 embarks are possible and that you are suggesting that other people should do it because it is fun. That would be better to post in the gameplay discussion forum rather then here.
They are not possible without dfhack. Thus, asking for them is indeed a game design change request.
I have heard rumors of 1x1 being slightly more unstable than other things, so there might be some associated bugs, not just changing one line in the code. However they are very rare bugs, I've done tons of 1x1s and never crashed. Including in mountains, oceans, the middle of villages, etc.
It depends on terrains I believe.
The game crashed several times on me. Once it was a volcano, the game will crash on start unless I change the location. Another time it was a cavern, the game crashed shortly after I dug to reveal a cavern.
And memery accessing issues don't always crash a program. For example, I had a program written in C, it had an array-index-out-of-range issue. It just crashed on some 64bit system but never crashed on my PC...
Oh, and I like the idea. 1x1 embark may improve the speed as well, which is currently my best concern.