Hi, I just purchased this program, and I wanted to add that I really like the Line Tasks. I'm all for making the task linking easier, but I also find a lot of use for just being able to plop down an arbitrary line too. For example, I like to add lines to break up clusters of tasks (like a divider) -- and these lines aren't attached to any task. So if you were to out-right replaced the line-task with some sort of integrated task-linking mechanism, I wouldn't be able to freely plot lines like that.
Also, being able to make polygons or other shapes with the lines is also a fun feature. I use them in a similar way as Lunarexxy -- to make "fences," graphs, polygons, and dividers.
So I would say: "Yes, absolutely make the task linking easier and integrated into tasks more organically" but also "the line tasks as they currently are are also useful for different non-linking purposes too!"
But as Lunarexxy suggested: the ability to just add more "nodes" onto onto a line (instead of having to make a dozen individual lines and manually link them up) would be a nice feature.