What AnemicOak said about longevity. It's a hundred(ish)-dollar consumer appliance in a rapidly evolving field; people upgrade because they want to more than because their device isn't working any more. And you're in a troubleshooting forum - you're going to hear a lot more about devices going wrong than you are about devices going right. Also bear in mind that when you're reading threads about Kobos bricking, a lot of the time it's because we're a community of hackers and tweakers over in the Kobo zone. This isn't always completely apparent from the first post in a thread
Word documents can be converted to epub for reading, but if you really want a portable solution to go back and forth annotating and editing Word documents in more than a fairly trivial way, you'll want a suitable netbook or similar.