Every single string gadget is something you cannot overlook. Especially, if you can enter values.
With your eyes and your mind you have to always consider what you are looking at, even if you know it well.
Now, if there is a value that is of no use to you as a pattern maker, but it's right next to the values you want to use, you always have to correct your gaze and your thinking to willfully ignore this extra GUI element. This is always unpleasant!
If you did decide to add degree for it, then you have to know what it is relative to. In the real world, for example, one would think that 12 o'clock is 0 degree, but in the graphics world, due to perfectly unknown reasons, somebody chose 3 o'clock as 0 degrees, which makes no sense to me whatsoever, but that's what it is. Now you have 1000 people and 500 of them know other graphics tools that fell for the 3 o'clock concept, while the other half is rooted in common real-world indoctrination, which has 12 o'clock as 0 degrees. Of course, only 1 of the 1000 actually cares about having degrees available for making a line, but at least 499 will be irritated about the wrong 0 degree origin, and 999 will be annoyed for life about having to worry about a meaningless gadget, stealing their focus on the actual work they want to do.

...you think that's worth it?
And THEN think about those, who were snapping to another tool as they add a new line! What kind of degree would they want to use? Should the degree be relative to the snapped line (0 degree continues whatever degree it was aligned by) OR if one went by a tangent or any of these... what would be the original degree then so that it made sense or was truly pleasant? Tons of things that would beg for more precision or clarity and still it would be 1 out of 1000, who would have 1 line in 100 lines where they wanted those degrees?
See, thing is, again, this is for making clothing patterns and is highly aimed at those. I must keep saying that, because I remember that I had the same trouble during the design of it. Always correct your thinking towards the most direct route it is aiming at!
This seems restrictive or limited at times, but really, it totally powers up the actual application of it!
Naturally, there are infinite ways to add stuff and details and obscure luxuries or even clear demands for certain other applications and so on... it's a computer program, it could be made to do anything. But this one is for making clothing patterns, which is meant to make it awesome for pattern makers, who suffer when they have to use AutoCAD or actually any other existing app for vector graphics, because it's a pain to use for clothing. This is where we come in!

NOW, I should add that we're still working to improve it, to make it even more solid and powerful and your suggestions already are WONDERFUL and the things you notice are extremely helpful! In every way I want to encourage you to continue to freely explore and think about any possible improvements, OF COURSE!

...I just like to remind you every now and then that it's not AutoCAD - "Me, too", but really its own special thing, you know.