The500man
All "logging of taxi time" discussions aside I commend you on your good airmanship for deciding not to fly that day. We taxi with the intent of going flying and a momentum and sense of expectation can develop that can be hard to arrest. As you correctly noted the demonstrated maximum crosswind speed is not limiting but 15 kts is the maximum demonstrated value for the C172. just because it is not limiting does not mean it should just be ignored. Flying is like everything else, you get better at it with expereince. Lower houred pilots should respect their lack of experience by giving themselves a bigger margin just as higher houred pilots need to respect the dangers of complacency.
advice to wait for the ATCO to call the winds at 15kts IMO misses the point. You are either comfortable to handle the 15 or 16 kt wind or not. The best way to develop confidence is to practice and this is where some flying schools with extremely low student crosswind limits (sometimes as low as 5 kts) are IMO doing their students a great disfavour.