You could probably compile the release version and change anything you want to, but that won't get you automatic updates.

As a fully open source product, with a demand and will large enough, someone could make a fork, even a minimal one, where they take upstream and keep this feature enabled. I personally don't think sufficient demand and will exists for that to happen.

I suppose they could make an about:config option out of allowing it, but really, so few users will probably find it so much of a problem that even a bug report/feature request for that probably wouldn't get traction.

They can't please everyone. Overall, it seems like a reasonable move to me.