I feel the same way about Pocket, and I didn't like the idea of Screenshots being merged into core (was a test-pilot extension for quite some time before). I have found though that Screenshots built-in is really nice for less technical users, especially for some more "complex" screenshot types, like webpage only, or full page screenshots. I rarely use it, but I've gotten many of my less-technical co-workers to use Firefox's screenshotting feature quite often.