The existence of hard-core secessionist sentiment predating and even trying to precipitate Lincoln's election indicates that secession in many states was more than just a defensive reaction to the election and Lincoln's policies. The ground was being prepared for years in advance.
One certainly can -- and probably ought to -- distinguish between the first wave of secessions and the last which did have more of a reactive character. Doing so indicates that Southerners, like Northerners, were far from united about what to do. But to leave enthusiastic secessionism and radical Southern nationalism out of the picture is to miss an essential element.