The parametric"cubic spline," say x(t), or x(u), has features not all of which are provided by Bezier or B-splines. The cubic spline alone provides continuous curvature, passes through all specified points, and allows the full range of end conditions. These end constraints are:
"flat" dx/dt=0 ; "stiff" d2x/dt2=0 ; "flexible" d2x/dt2 linearly interp. from neighbors
"slope-set" dx/dt = x.xx (user input)

An introduction to the topic is provided at my website www.HowFliesTheAlbatross.com but the code has been streamlined and revised since it was posted. The theory and VB code are available as an updated Powerpoint file upon request. The latest approach is as follows with user-set values at each end for a "constraint" parameter:
[0: flat] ; [1: stiff ] ; [2: flexible] ; [+/- x.xx: slope set]

Could the experts at Blender add this feature? This is particularly suited to aircraft and other objects where we must maintain continuous curvature and pass through all specified points with complete control of the slope or curvature at each end.