Except the issue with that last one is if they are going to be mains LATTER then it makes perfect sense. I have seen this with other stories and even had Authors talk about how characters they didnt realize were mains were.
So just because its not NOW doesnt mean they wont be later.
As an example let us take "One Way street" from Index he was a villain and a seemingly nasty piece of work later on bits morphed him from a villain turned side into a Main character.
JNPR is the same Monty caught it though BEFORE production that they will be Mains hence why he said they are.
They just havent reached that point yet is all which is common in many stories.
The issue with saying episodic vs Movie is that it may not be possible due to File size and other like things. Also when people say it works better seeing it all together is they are talking more about the wait time between weeks were people working themselves into knots.
I can tell you ANY anime works better when viewed as a whole then episode but time managment and resources make it not a doable subject.
So that isnt Fair because it ignores what people are talking about when they say it flows better. People work themselves up over issues or nitpick a small issue into a giant issue and so forth.
The wait time and the problems it causes is what people are REALLY talking about.
The issue with Mistakes is that happens period. I have seen it with big name shows with a LOT more resources then RT does. The question is not are they going to make mistakes because EVERYTHING does the question is what are they doing about them.
Which RT is trying to fix them.
And something to keep in mind is that RT might be in works to generate a second sister series to RWBY which RWBY sets the ground work and the sister explores it.
As an example of this take A Certain magical Index which has a later sister series that got started WHILE Index was going called a A certain Scientific Railgun.
Index follows Touma and his adventures with Magic Espers and so on. Railgun follows Misaka and her adventures while being invovled but unaware of Touma's often exploring things with a different perspective.
The 2 together create a richer story then either by themselves.
Mind you that is just a theory but they have talked about this before though in terms of AFTER RWBY is done as far as I am aware.
What I am trying to say though is there might be more going on then we realize which makes stuff LOOK odd when its got GOOD reasons for it.