Looks like stock O2 sensor is a narrowband.
There is no meaningful adaptation occuring to compensate for more air flow. At best, only the archaic long term trims based on part throttle use and a model of fueling required (when equipped with the restrictive stock filter).
Sprint are less than ideal, stick to K&N or DNA if you want air that's actually filtered. Sprint race line filters can flow the most, at the expense of the largest particle size filtering (regardless of their marketing). There are so many pictures of sportbike guys using them that had dirt/crud in the air box using a Sprint I won't bother linking. It's trivial to find.
Is a retune mandatory? No, not entirely necessary to simple ride the bike.
Should a retune with O2 disabled be done? Yes, absolutely because the fueling will be incorrect without fail after swapping.
Running and running right are not the same. The bike will run with a rubbish tune but it won't be right.