I see most people just like to read the headline then head here for a quick rant.
I can't see any issue with what Mozilla are doing here.
To all the people who can't be bothered to read the article, you'll only see these "Adverts" if you install firefox on a new computer and you will only see them until you have visited 9 different websites.
If you are already using firefox then there will be no change, once you've been using firefox for any normal period of time it will be no different to how it is now.
This is no different to the way the start screen for firefox is a google search page.