Am I not using the step sequencer right? I ask, because I see Insert Row, but not Insert Beat.
 
Why is it necessary to insert one or more beats?
 
I'll often be working in the step sequencer and realize, 'Wait, I want to make a part longer or add a transition to the next part I'd already added within the step sequencer.'
 
But how do I have to do that within the step sequencer today? I have to manually move over each note I'd already added so I can insert the necessary notes to extend a current part or add a transition.
 
Please help us speed up our workflow by adding this feature.

If the sequence is still "raw", I mean has no applied parameters like swing or other "mods", there is quite fast workaround: "bounce" the clip, split it, move the right clip required number of beats, bounce both clips into one again and convert into step sequencer.