You don't need to assign a different style to every layer; you could have "Thin" assigned to multiple layers which are supposed to be plotted with thin line weights.
Just like color based, it shouldn't be left to the user for the most part - automation should select this so the user is focused on the design, not fine tuning the settings.
It's easier to "bulk set" values with CTB. Its a lot easier for an STB-based drawing to end up with parts printed in color (or a B/W printer approximation) due to missing style name, "Normal" style, and so on. And yes, B/W printing is still the most common.
STB printing can get funky and frustrating when dealing with XREFs.
It's easier to print "blind" with CTB than STB. If the drawing has a bunch of unknown color settings you just use a CTB file with all colors set to plot at a medium line weight. If a drawing has a bunch of miscellaneous plot styles (my favorites are "Style_1, Style_2, etc." and "Fred, ClientName, etc.") you need to create a specific STB with those named styles.