Yes, the labour laws there suck and are in much need of reform, but the levels of criticism this has reached crosses into downright racism.
Since we are on the topic of slavery. What about the millions of undocumented workers in the US, who work below minimum wage, have no rights, and no protections afforded by the law- They are effectively slaves working under the threat of deportation. The idea that US government cannot do anything to stem the flow of illegal immigration is ridiculous. We are talking about a country with military/police capabilities larger than the remaining top 5 countries combined. The fact of the matter is the US economy benefits from having a low-cost, migrant population with no rights, just like Qatar, and the government isn't in a hurry to fix it.
I would rather a World Cup be hosted somewhere in middle-east,Asia or Africa instead of yet another country in Europe or the Americas . India would make a great host if it could afford it. But we can't, and neither can many Asian/African countries. If the Qataris can and are willing to do it, give them a chance.
Edit: It's also amusing to find everyone on this thread and the internet up in arms against Qatar/Russia for all the bribery and corruption, when the indictments so far actually relate to corruption going back 24 years for matches in the US, South America (according to BBC) and the previous World cup in South Africa. I don't remember anyone complaining about corruption back then.