It does seem as a great marketing move which would increase global attention and potentially foster acceptance. So why not.
Because in all honesty it would just be seen as a joke. No one really takes these midget nations seriously (not to mention it's usually in disputed territory between other countries - so these micronations may not even legally exist), it would just bring a bit of attention. In reality, there are many, many better ways for Bitcoin to gain attention and hopefully adoption (i.e. acceptance by a big merchant, integration into everyday commerce).