Here's the thing: PDF is a page description language. This is quite different from a stream of text with some markup inserted (e.g. ePub). The vendor of your old ereader decided to take a chance at being able to take a PDF file, pull out the text, and reformat it properly. Maybe that always worked for you given the types of books that you read, but it does not work in general. The types of publications that I've read produced everything from random spacing, to mixed up passages, to garbled text, to nothing at all. It is quite probable that Kobo was left with the option of adding a feature that produces unpredictable results or leaving things as they were and decided that the latter is the best option. After all, unpredictable results result in more calls to technical support and poor reviews.