There are a ton of large-screen tablets that are made for pdfs and all that stuff...I use my pad, which works great for pdf for books and documents. Rejecting a 6" ebook reader because it can't serve specialized techie needs is like rejecting a cell phone because it can't take photos like a professional camera. I'm sure you could get a good deal on a used Kindle DX, I can't imagine why Amazon stopped selling them, with the overwhelming demand for pdf/tech document/graphics reading on eink screens.
For the majority of us who just want to just read books, especially epubs, without extra light, it's perfect. Plus we get to help support an alternative to the Amazon/BN dominance of the ereader market, and give a little support to indie bookstores who sell Kobo.