Antarctica is the last unsettle continent on earth, and for very good reason. It's the coldest place in the world and one of the most barren resource wise, and by treaty no country actually owns it (nor would want to). However because of it's barren remoteness it could make a nice testing ground for prototype extraterrestrial habitations.
We would need to in the future because of the growing population of earth but for now it is unnecessary and frankly very costly, but because of or growing population we are always going to nee more space so its going to be Antarctica or the moon. I vote on the moon personally.
This is a bad idea because the amount of resources necessary to support a city in Antarctica would be enormous, costly and have an enormous negative ecological impact. Furthermore, extreme polar regions are far more environmentally sensitive than non-polar regions and can take hundreds of years to recover from any environmental disasters/mistakes that normally take only a decade at other latitudes.
Transportation and construction costs would be extremely expensive, and it would be extremely dangerous. The temperatures are many times well below freezing, and the average wind speed is about 50 miles per hour (80 kilometers per hour). The harsh weather conditions would impede progress and possibly even take many human lives.
In addition, Antarctica is barren in terms of needed resources. Fresh water isn't that much of a problem, but food and building resources are. The harsh conditions prevent barely anything from growing, so food and lumber would have to be shipped from somewhere else. There is no way Antarctica could easily be self-sufficient.
The living conditions would also be an issue. Roads would be under constant maintenance because of the snow and ice burying and freezing them over. People also wouldn't be able to stay outside for very long because of the horrible weather.