I never really thought about it much, since what I have done previously is draw in notes as quantized values (not very musical at best, mechanical at worst) but over time I have since altered note lengths to emulate guitar strums or keyboard hand movements.
The problem is of course when you cross a bar line, so for convenience I try to start notes after a bar has already commenced, in order to be able to cut on the quantize line. It may not be so important where something ends since cutting of the part can take place at a later point but it would be great to be able to determine this point in deference to a bar line.
While I can see why the modifer would only work for both beginning and end points in its’ current (default) state, it would be great to be able to choose, as when you are programming tempo; sometimes notes need to be elongated.
While this elongation mostly occurs towards the end of chord/note sections, as they blend into new parts, it would be nice to be able to cut parts at any arbitrary point while still allowing a quantize value to be selected.