Comment 6 for bug 184550

inkscape prefs > misc > simplification threshold

i'm not saying this closes your report. i'm just pointing out that you can simplify softer if you want.

the current parameters of the calligraphy tool have been very extensively tweaked to provide natural-looking results, exactly preserving even the very fast movements of the pen. this is a must for freehand artistic drawing for which this tool is designed. muffled, melted and oversimplified strokes are no fun. we intentionally chose precision over saving a few bytes, and personally i don't think the tool produces too many nodes. imho, just enough for the kind of shapes it creates.

for the rest of your requests on removing subpaths, this makes sense.