Every time a Mozilla article is posted on Slashdot, the entire conversation just becomes a huge slag-fest. You would have thought Asa Dotzler shot their dog.
Mozilla is a fairly large company. It has resources to do more than a single thing at a time. As long as those things generally fall into their "Free, Open Web" philosophy and don't completely sap their ability to pump out Firefox releases, who cares?
In the same post, you will have people complaining about the feverish release cycle of Firefox and also complaining about how they've "abandoned" the project. Or complaining about issues (like memory usage or speed) that haven't been true for years. Firefox is certainly within the ballpark of every other browser when it comes to speed, memory use, standards compliance, promptness of exploit fixes, etc. There are a few areas (multiprocess and 64 bit being primary) where they lag.
All the freaking whinging about the Australis GUI (when you can get extensions that will drag you right back to 1999) or frequent release cycles is ridiculous. Mozilla always tried to be competitive with other browsers. Four years ago, people complained about slow release cycles vis-a-vis Chrome or talked about how clean the Chrome GUI was - Mozilla listened to those complainers and got a new set of complainers.
There will also be a bunch of people recommending Pale Moon or Iceweasel or whatever. Those browsers wouldn't exist without Firefox - if Mozilla goes dark, those projects will run out of steam very quickly. It's healthier to look at them as distributions rather than alternatives - tweaked to a specific user base.
I like Firefox because the extension ecosystem is still miles better than Chrome after Chrome has had 50+ releases to become competitive. I like Mozilla because they at least give one crap for the concept of a free, open web that isn't incessantly spying on you.
This isn't to say Mozilla is perfect - they've certainly screwed up their share of times. But we should want a healthy Mozilla out there - your alternatives are Google or Microsoft monetizing your every click.