Couple of reasons for the "hard bends".

1. Manufacturing. Yes, you could do it as smooth, flowing curves since the molds are now machine cut. But, it is more difficult to fit and press together long, flowing curved joints than a series of straight line joints. You also notice that most wings have distinct taper breaks, and not the "elliptical" planform (SZD-55, PW-5 and PW-6 are exceptions).

2. Ease of repair or refinish. Ever try to make a sanding board to perfectly blend a re-pair or refinish on a continuously varying radius, 3D part?

The changes in dihedral are small enough to not cause any significant issues. Similar to the changes in taper ratio at a taper break. Yes, there is a change in the pressure field around the wing at each of these, but there is negligible impact until you get to much larger changes in taper ratio or dihedral than are used here.

To my mind, the real benefits of the changes in dihedral come about in the outer at most 1/3rd of the semi-span, where you can make the downwash field behind the wing work to keep the tip votrex from shrinking the span of the downwash field.

But, that is just my opinion.

Steve Leonard