Yeah, having geometric continuity per mouse click or keystroke would be nice. At least you can achieve that by “playing around with the control points”. But doing this always manually can make you angry sometimes.
For the MonoGame.SplineFlower library I plan to add at least parametric continuity (BézierSplines & CatMulRomSplines), so that particles or a spline walker can have the same velocity or acceleration over time.
Regarding CatMulRom-Splines there are also other tricks like adding or removing tension to a curve to make it sharper or softer. In combination with an alpha value 0-1f you could have a pretty nice control over your generated curves (0 = uniform, 0.5 = centripedal, 1 = chordal [inclusive all the grey-zones]).
But I don’t know if this would be good enough for 3D-Development.
I think they invented NURBS for a reason