Bad comparison. A car needs the required parts to function. An already-working game with just one added scene will still work.
The rework could have been broken down into multiple updates, as one update is a monumental task that takes years to complete. Of course, what's the other reason one update takes years to complete? Maybe it's not too late to buy land in the Chronicles of Elyria.
The already-working game is the version out now v0.20.16. With parts of the code still needing reworked and the posing only partially complete for the change from 4:3 to 16:9 display ratio - there is no version that can function on its own at this time.
Could it have been broken down into multiple updates? Maybe, maybe not. I don't know and you don't know. It's merely conjecture. What part would you want done first? The 4:3 to 16:9 display ratio? Along with that display ratio change needs all the posing for those scenes to be redone. Note that posing is not complete by the posers. One reason why: the posing required new coding for a posing system that would work. Another reason: renaming the layers which go into posing into a consistent naming scheme.
The hodge podge of the current code is a major reason why nearly the entire code is being revised because, as it has been stated, for all the frankensteining done over the years - it's luckly the game works as it is. If you want to just continue to hodge podge code bit by bit it's only moving the problem down the line and not addressing it now.
It is actually an apt comparison if you consider that in order to do one thing for the update, several other things have to be in place and working correctly.