When Katniss Everdeen visits what is left of District 12, we see loads of dead bodies (well, what's left of them) and the destruction of the entire place. We then see that Victors' Village is pretty much untouched. What was the reasoning for this?
Whilst answers from the movie are always good, the Mockingjay novel discusses this in its very first Chapter. It states:
Almost nothing remains of District 12. A month ago, the Capitol's firebombs obliterated the poor coal miners' houses in the Seam, the shops in the town, even the Justice Building. The only area that escaped incineration was the Victor's Village. I don't know why exactly. Perhaps so anyone forced to come here on Capitol business would have somewhere decent to stay. The odd reporter. A committee assessing the condition of the coal mines. A squad of Peacekeepers checking for returning refugees.
At the end of the first chapter, Katniss discovers a fresh white rose among dried, dead flowers on her dresser. She realises immediately that Snow has sent it. Quoting again from the book:
When I begin to gag at the stench, I back away and clear out. How long has it been here? A day? An hour? The rebels did a security sweep of the Victor's Village before I was cleared to come here, checking for explosives, bugs, anything unusual. But perhaps the rose didn't seem noteworthy to them. Only to me.
In her eyes, Snow left the village standing as a personal message to her about her actions and the pain he could cause her. However, there was also a side effect of doing this which was that any official Capitol citizens had somewhere to stay if they ever had need to visit District 12.