Note that it doesn't just suck because you're giving up using the Kindle itself. It also sucks because you'll be losing your entire collection of Ebooks, which are DRM-encumbered and can not be ported to other non-Amazon devices/platforms/apps.
This makes it extremely difficult for other privacy-respecting platforms to compete on the market, since using them requires the user to either break the law by stripping DRM from their books, or to abandon their entire purchased library.
Future TOS/EULA/Privacy changes that might not have been in place when a user originally bought their Kindle can thus be forced on them by making it prohibitively expensive for the user to opt out or change ecosystems.