Since Rhino 7 has a great ! _ExtendDynamic _Pause _Type=_Natural command that does not add extra control points and preserves the structure of the extended curve, why does the ! _Connect command with the “ExtendOtherCurvesBy=Smooth” option change the structure of the input curves by adding extra an control point to each of them? Is not it more natural for the ! _Connect command to use the same approach as the ! _ExtendDynamic _Pause _Type=_Natural command? 
Original curves:
Extend natural preserves the structure of the curves:
Trimming of the extended curves preserves their structure:
Connect with the “Smooth” option destroys the curve structure by adding an extra control point on each:
Thanks!