I read quite a few PDFs and don't actually have any complaints. I am not personally seeing any readability issues and don't mind consuming PDFs at all.
That said, I think I now understand your complaint. Thanks! I just don't personally have any trouble with it. I use multiple tablets, of varied sizes, and I've had good experiences with all of the devices. While some PDFs are horribly formatted, I find that the device choice doesn't help that and it's a design choice from the author.
But, again, thanks for helping me understand.