So...why did BW completely rewrite Krogan society?

S omething had to change for the Krogan colonists to survive.

J ust it came in the form on rewriting lore.

W hy they did this i have no idea i have always enjoyed Krogans history and setup.

Well, before the genophage, there were female Krogan warlords. We hear about this back in the original trilogy. Of course, the genophage changed things, but I guess after coming to Andromeda, combined with the fact that Clan Nakmor seems to be adapting to the geneophage or something (I think they said their birthrates increased by a small percentage in the game), they decided not to keep things the way they were in the Milky Way.

The Krogan in Andromeda are looking for a new start and they definitely don't have the numbers to be fighting and killing each other over females. I'm sure it also has to do with Bioware wanting to show off female Krogan more since we didn't see much of them in the original trilogy. Could they have done a better job of this? Obviously, but it doesn't bother me much.

They didn't rewrite anything.

From ME1 we know that mostly it's just male Krogan that leave Tuchanka and that they leave to become Mercs, which is why we see just see male Warriors.

In ME2 we learn the following things about the Krogan:
Multiple Krogan talk about how each Krogan clan has their own culture & society, so not all Krogan clans are the same. This means that we can't take everything we've seen about the Krogan in general and apply it to all clans
There are such a thing as Krogan scientists and engineers
Women have their own clan structure that is viewed as equal to the male clan structure (Wrex says he can hardly do anything without the approval of the female clan leader)

In ME3 we learn that Krogan seem to have no issue with following a woman, given how Wrex experiences no blow back when choosing to share leadership with Eve.

All MEA does is expand what we already know about Krogan and Clan Nakmor.

What are you talking about?   That was pure cinematic brilliance!

I got an idea, patch it so they are hitting each other with handbags!!!

I really like Kesh and I think we see a fair amount of her, but then I was constantly popping back to her office to have a chat with her and her dialogue does update a few times. Whereas I ignored Tann unless forced to talk to him.

My major issue with Morda is that it seems like some of her content was cut. Unlike other settlement leaders, you don't get a chance to speak to her outside of story missions, so I've really no idea what she is like. From the book, she seems like a cool character, but none of that comes across in game. 

New lore - this is now how Krogan fight moving forwards in the series.

Funny thing is I remember a youtube vid talking about the dialogue in MEA on how it was very sitcom-ish and they played a laugh track behind a few conversations and it fit perfectly.

Not sure if I should or :sob:

From what I've seen they didn't rewrite anything. Only issue I see is the Krogan won't expand much. These Krogan still have the Genophage considering the Arks left prior to the Reapers arrival.

Alright, but you still can't convince me that's how they fight now. No... way....

Mac "what the hell is lore" Walters, Creative Director, everyone.

Wait, I am actually not quite getting this. What are you saying? Are there indications that there was some kind of cast system in Krogan society in ME1/2/3? As far as I recall, Krogan scientists held positions of honor (Okeer for example or that scientist in the lab on Tuchanka in ME2). I also didn't get the feeling that workers or mechanics (like the guy who works on the Tomka in ME2) are seen as any less than the straight up warriors. The shaman outright tells you this when going on Grunt's LM "Not everyone can be a great warrier but if you can't inspire your crant to fight for you, you better go out into the wastes to die". From this, I take it that they value the ability to excel at something, not just to fight.

As for the women, they were always held in extremely high regard (at least the fertile ones) and kept isolated and protected as a consequence of the genophage. It makes perfect sense to change this now as something happened to genophage (it's lessened maybe? I never quite got that one) and since the Krogan are trying to start a new colony with just a handful of individuals, which means they need to all work and live together if they want to make it. There are actually some email messages on the terminals on New Tuchanka that mention the the everyone needs to try and adapt to the new ways in order to make the colony work.

While I too am not entirely happy with the depiction of the Krogan (they are a but too nice now), I don't think too many changes were made in terms of their society and those that were made make sense to me.
But maybe I misunderstood you.