I am speaking as a user of the product and offering feedback - the whole point behind Tor is to protect your anonymity and that's hard to do when the browser itself is leaking your IP (and other data) to some service you don't even care about. At best, such kind of integrated services should be opt-in only by default. (Note that Firefox services are now opt-in too in Tor).
Tor Browser is 100% open source, so pull up git and run blame if you want to determine the reasoning for a decision.