easier roll cast with double tapered
another reason some people might like DT lines is that itīs easier to do the roll cast with them. Since the line has a tapered design the energy transfers easier from the wider and heavier middle towards the light and skinny end when you are flicking the line
On the other hand, with the Weight foward lines you have to roll the heavier end using the lighter middle, so itīs trickier.
For regular casts, WF lines are more convenient on windy conditions.