Why shouldn't it be? They did steal it, and it was probably pretty expensive. And some poor fat-assed shopper didn't have a cart to ride while they shopped that day.
Because it is an escalation that does not need to occur. With more and more offenses becoming felonies, the “raise the bar” mentality of legislators will come to a breaking point, where everything is a felony. These folks would be better served with a sentence of community service but now are facing 2-3 years.