"Although, I never saw what the issue was that caused all the....fuss over the old GUI."

That's the thing. A philosophy of vocal long time users resisted progress, making PGM tread water by maintaining a balance between moving forward and cater to conservative voices. At the end you had a very capable software that was nearly impossible to break into- alienating newcomers. Mainly because features were implemented in a way to avoid conflict with selected few, and not what is best for the future of the software.

Some of solutions going forward included making BIAB more coherent and modular. Two major steps were taken: Bringing all creative content under one roof - Library, and UI that is modular and logical. Still whole bunch of known issues that kept BIAB anchored to the past left to resolve, but I feel now it's on the right path and hopefully will appeal to a much wider audience, without sacrificing core value.