Airport firetrucks commonly use foam because kerosene (which jet fuel is) will usually float on the water. Spraying it with water will just spread out the fire. Inside a building, water could be useful in lowering the temperature which could reduce the damage. I've read some reports that most of the jet fuel had been consumed in only 5-10 minutes. According to those reports, the rest of the fire that ultimately caused the collapse was caused by interior furnishings and materials. Functioning sprinklers might possibly have delayed the collapse but they might not have been able to stop it. The first article I linked mentioned that the towers were designed to survive a normal fire for 3 hours without any sprinkler system. Even though the towers were designed to survive an impact by a Boeing 707 sized airliner, no one anticipated the damage from a heavily fueled plane like a 767. Hell, Boeing hadn't even began the design studies for planes like the 767 when the WTC was designed.