Earlier quoted context omitted.
The right thing to do would have been to work on those extensions BEFORE breaking users' experience.
Mozilla doesn't create all those extensions. And the extensions' authors had, what, two years advance warning or so? Criticize the real culpits, not Mozilla.
Obviously I paid nothing for Firefox and Mozilla owes me the same nothing in return, but if it wants to keep users and remain significant, breaking arguably its main advantage might not be the best plan.