The thing about Scud missiles is that they're not a precision weapon. Their accuracy is measured in the thousands of feet. So just by firing it at civilians, you show you don't really care where it lands. And in a war with more than 170,000 dead already, that's not surprising.
Considering that another weapon of choice of Assad's forces are barrel bombs dropped from helicopters, the use of Scuds by Syria's military seems like a likely, but still disgusting, evolution in tactics.
Seeing as these theater ballistic missiles have little use against actual rebel targets, they are more likely being used as psychological and area effects weapons, similar to the Nazi V-2 rockets of WWII, from which the Scud was derived.
Syria possesses a large arsenal of Scud missiles, thought to amount to about 1,000 missiles, including the highly inaccurate and relatively short ranged Scud-B and C versions, as well as the much more modern D model, which can reach out to over 600 miles. These mach 5 capable ballistic missiles can carry various payloads, including 2,000lb high-explosive, fragmentation, chemical and nuclear warheads.
Since early 2013, it has been known that Syria was using Scud type missiles to hit areas in Northern Syria, the results of which have resulted in very little tactical gain but have killed hundreds of civilians and flattened scores of homes. Syrian officials deny the claims that any Scud missiles have been used in the conflict at all. Yet Scuds are not the only ballistic munitions Assad's forces have used on areas where Rebels supposedly persist, recently a video surfaced of a multiple rocket launch system attack on a Syrian town.