I guess I have something more to add, after all:
- When I need to replace my ereader, I want to be able to pick the brand and model that has the features I want to a price I like, without having to choose between staying with my current brand of ereader, or else having to redo a lot of my library organization. Therefore, I would never buy a brand of ereader that required me to use the brand's proprietary system for organizing my books.
- I think huge, powerful monopolies are bad, and want to do my (small) contribution to refrain from adding to the power of the most powerful of them. Therefore, I want to reduce the amount of money and information I give to Amazon (and Google, and Facebook). I'm not willing to boycott them completely, because sometimes I'll prioritise my convenience, but I'm willing to do a bit of effort. (This wouldn't keep me from registering a Kobo, so for that only reason 1 applies.) And sure, my individual contribution here is a drop in the ocean, but like Difflugia said, so is voting.