You could be right about flexibility, although most solutions are open-source and you can always find UIKit/CoreGraphics libraries specifically for drawing shapes/lines.
There are Sparrow 2.0 extensions for drawing polygons (and circles from high-count polygons). I also created a Sparrow 2.0 extension for lines, but it uses Core Graphics to create a SPTexture of the "line". So the initial loading performance wouldn't be as optimal as drawing lines directly in OpenGL. I went the CoreGraphics route for rounded edges, anti-aliasing, and simplicity.
As for CocoaPods. I had my doubts due to unfamiliarity of it, but after digging into it I think it can be far more useful for managing multiple third-party libraries. It is also fairly easy to install. I personally haven't used CocoaPods in my own projects yet. If you don't using more than a handful of libraries in a project, I don't think CocoaPods is really that important.