Sadly it was necessary. I'm a solo dev and this is my first game. I promised everyone when I started that updates would be weekly, and aside from the (voted on) delay in getting the combat system in place I have stuck to that for over three years now.
Unfortunately there's a limit to what a solo dev can do with only a week to work on each update (especially taking bugfixing, community management, compiling, marketing, repos, tech support and life in general into consideration) and so I had to choose whether to break my promise or stick to it, even if it meant that Act Three started out very barebones. For better or worse, I chose to stick to my promise.
I completely understand players' frustration in going from the fleshed-out Act Two (which took two years to create) to the very sparse Act Three, though. Hopefully the promise and potential of Act Three keeps people going, but to those who are more annoyed than entertained I strongly advise pretending I'm one of those "update every four months" devs and checking back in on the game around June. Should be a lot more to do by then! ;)