I don’t know if it’s on purpose or just some collateral effect of the brush engine that some brushes require a “larger” pressure level to even get them to paint any pixel at all.
If that’s on purpose I don’t get why it exists, I think it’s arguable it would be good to be able to toggle it.
If that’s just a byproduct of the engine, I imagine that’s possible to somehow make it so that any brush (any brush that doesn’t paint even without touching) would start to paint even by the slightest touch (the minimal pressure one hardware’s detect), preserving proportionally the pressure curve set-up in the brush settings, of course.
The motivation is solely ergonomy. In an ideal world, the stylus would be able to work pretty much as a felt tip pen, with pressure that’s not even detectable by hardware (at least not mine). This would probably be the closest possible to get to this point, via software.
I can’t even guess what kind of challenge it would entail to implement.
I imagine there must be something along the lines some kind of function that calculates at which pressure the brush starts to actually paint, and then discounts all its pressure settings by the same amount.