I know that this is an old thread but i would like to add in my support for something like this as well.
Though, from the other thread, it seems that a set of actions that would work with these kinds of features would be in need of an array handling system. so, I wonder if it were made so as to work with Array maker (which i would love, love, love to see integrated into Playmaker itself... as long as Jean is okay with that though.)
barring an array handling system, a workaround for now might be to see about having an action set that has something like three or four iterations? one with a single point-to-point line-renderer system, another with a point-to-point-to-point... another with a point-to-point-to... ahh, you get what i'm trying to say i hope.
and for the more than two points, have a toggle that will allow you to close off the spline?
i have just started reading up on the line renderer though (it would allow me to make this lightning effect i'm looking for for one of my games... also, it'd also maybe let me approximate an effect like the ghostbusters' proton packs from the most recent ghostbusters game.)