There's no "right" to an increase in benefits. Social Security payments are supposed to adjust with the Cost of Living. However, if the cost of living goes down, payments don't actually decrease.
The last increase was 5.8% due to a spike in energy costs. As energy prices have stabilized, the argument is that benefits are now catching up to what they would have been without the raise back starting in 2009.
The failure of having a social security increase in 2011 is troublesome to democrats, who are slated to lose a number of seats in the 2010 mid-term elections as it is.
With the average Social Security recipient receiving $1,072 per month and 2/3 of retirees living on Social Security alone, Nancy Pelosi pushed to pass a $250 one-time bonus payment to recipients. However, passing this in the Senate will be difficult, at best.