"This helps us [...] providing a browsing experience that is more tailored to your needs"
How would my browsing experience be different in any of the categories? Unless it's about showing me ads yet again.
If the categories were things like "using search as the most convenient way to find a well-known website", "entering a term that's likely to appear in a news headline", and "asking a fully-formed question", I'd find the claim that this is about ways to make a better "browser experience" more convincing.
Mozilla is supposed to be better than this. I don’t really see anywhere else to go though if you want a web experience that works out of the box (non-free codecs and the like).
This. It's not necessary, and I consider it dangerous. Even if the browser maker is 100% on the same privacy page as I am, browsers are too complex to trust with personal data.