Sure, buying is cheaper than renting right now, but good luck trying to buy.
Some issues:
A bunch of people are underwater on the homes they own. They can't buy.
A bunch of people have black marks on their credit from recent economic troubles (foreclosure, short sale, or simply being late on bills due to job loss, etc). They can't buy.
A bunch of people are unemployed. They can't buy.
Larger down payments needed nowadays. Anyone with trouble saving up that much money (and everyone here has read stats on how most Americans can't even access 2k in a month) can't buy.
Appraised values of houses may come in too low when selling. If this happens, one can't buy. (For example, I had a deal fall through recently cause the appraisal came in about 10% below contract price and the seller wouldn't budge on price.)
And in general the credit markets are so tight even people with good credit scores and a good down payment may struggle to find a lender.
Not to mention the deflationary type problem going on in housing right now. House prices are still going down, so even if it's cheaper to buy than rent, it may still be better to rent and wait for house prices to fall even further.
EDIT: Just read the article. Vegas was their example of the cheapest place to buy instead of rent (Disclaimer: I live in, and invest in real estate in, Vegas). Yet Vegas home sales, in the past year, have been approximately 50% cash purchases by investors. There's a ton of places for sale, but too many people having trouble qualifying in this credit market, so less sales than there could be, leading to half of them being cash (that would be a much lower percentage if more could qualify for mortgages). I also forgot to mention in the above list that make buying difficult: many homes are cash only sales. Good luck raising that much cash, for the average person. And many homes won't meet appraisal because the inside is wrecked, or the AC is missing, etc. All of those homes can't be purchased by an average person, only someone with cash to fix it up.