We don't make changes arbitrarily (and we try to explain the logic behind things in most cases). Some things work and some things do not, but we're always thinking about the betterment of the community overall. Also, you've missed the announcement that came with the changes that may have partially helped to explain:
Users can now upload their avatars directly. The placeholder is necessary for design purposes. We already came to the same conclusion, that Gravatar, while a great tool that we appreciate, isn't the best option for everyone.
We care very much about the community and the user-friendliness of the site, hence why we accept and respond to feedback such as this very quickly and honestly instead of it simply disappearing into a black hole like most sites or getting a useless canned response of sorts.
We understand very clearly that we didn't build NTM, you did, we just posted a sign up sheet on the wall. From day one that has been our mindset and we have always followed this principle and the community has always had a strong influence on the evolution of NTM.
We're always here to give back to the community, whatever they need, but we do need to hear these thoughts here in the feedback area because without fresh eyes we're not always going to see the same things. All we expect in return is for people to have fun answering questions.
Thank you very much for your well-needed feedback, which we check on everyday. So, remember, we're always here to help, but we can't always answer unless someone asks, so if anyone has any other requests, questions, or concerns (no matter how seemingly trivial), we want to hear about it:
The door is open 24/7. Thank you!