Pipes like most linear objects like columns, beams etc etc do not get placed like your typical one insertion point object Cell. Placing the 'pipe' Parametric Cell then measuring the correct length then going back to the Properties dialog to type in the length is for the birds.
The place pipe tool workflow should be at least TWO points. Again this is typically provided by the code written by the vertical tool's author.
Parametric Cells need to cater to not only 'point' type object like chairs, doors, windows.
The Place Parametric Cell dialog already offers up 'Local Variables' as an option. It should also offer a By '2 points' or By Measurement option. Even the old Place Cell tool accepts multiple inputs when the 'interactive' option is selected.