Browsers just duking it out on features and ease of use is not how the browser market works—Google can and does leverage their dominance in non-browser markets to boost their browser, and Mozilla is not going to raise their browser share against tactics like that if they simply focus really hard on making a better browser.
Tying it to a more functional goal like successful diversification of revenue makes much more sense (even if you disagree with how they did it in this particular case).