Only the Raen, and that's because they're part of Doman (the Japan analogue) society. We know literally nothing about Xaela societies, other than that they're nomadic, warring tribes that inhabit Othard's western steppe. Popular belief is that this means they're the Mongolian analogue, but we don't know that.
On Foodstuffs
-The plains American Indians aren't a good comparison to Xaela. They inhabited, y'know, plains, not steppes. Steppes have far fewer game animals, so the people who inhabit the region have to maximize the efficiency of what they have. Excessive musculature uses a lot of energy... we've been over this before.
The Xaela probably don't have large game animals like bison to provide plentiful meat. Small antelope is the best we're lookin' at, going by real-world examples. The available diet has a great impact on physique, and without frequent sources of calorie-rich foods they'd have a smaller and slimmer physique with more efficient musculature.
(So the real question isn't why are Auri females so tiny compared to the males, but why are the males so massive compared to the females? Seems like the same question, but it's not.)
1. Maybe insects aren't the best example, but let's look at a human example then: Bruce Lee. 5'7" and some change, between 135 and 160 lb, still renowned to this day for being one of the strongest people to ever live. It's not about muscle size, it's about efficiency; for all we know Auri women simply have much more efficient muscles than the men. Considering the size gap, without anything stating the women shy away from physical combat roles I'm inclined to believe this.
Can't say anything about the lack of muscle definition, but even the males aren't particularly cut. They certainly appear stronger thanks to their greater height and proportionally larger muscles, but we've been over muscle size before.
2. We don't know if Au Ra and Hyur are capable of interbreeding. They might be unable to produce viable offspring, so Raen genes would be unaffected by interbreeding with Hyur, leaving them with the physique of their Xaela ancestors. Urban life doesn't exactly favor particular traits, and without a significant amount of time (think hundreds if not thousands of years) for evolution to differentiate the tribes, there would be only cosmetic differences (horn / scale colors, a greater incidence of limbal rings among the Xaela, etc).
3. Nothing much to argue against. Original point is they can't change the design of Xaela females in the future because then they'd have to give everyone another free Fantasia. Yes you pay for the VR one through sub fees, so it's not free free, but you get the point.
4. I can understand that sentiment, not wanting to use a Fantasia to race change. I debated doing so with my VR one, but in the end decided just to tweak my current appearance. I didn't consider doing so to change to an Au Ra until I realized how much damn time I'd have to spend getting my crafting / gathering professions up again.
Still, you're not helping the case for sturdier females by playing a Miqo'te.
I won't just tell you what you want to hear, that "I understand and that's cool". If you're not helping, you're part of the problem.
In regards to moeblobs and bishoujo stagnating the game just like the anime industry... it's a possibility. Definite possibility. If people stop playing because of the character designs, and nobody uses the moeblob / bishoujo designs, they'll change things up. 'till then, though, they'll do what's known to sell. It's a pretty shortsighted way to think, definitely, but it's not up to me to try and tell SE how to do their business.
(Personally, I'm too invested in the story to let moeblob race designs stop me from playing. But that's just me.)
It's too early to make a judgment call on that issue, though. For all we know they won't introduce more races, or the new ones will have fit females and doughy males. There are infinite possibilities, so being up in arms over female Au Ra and stating they suggest all future female designs are going to be moeblobs is... I dunno, I don't wanna say silly. Presumptuous? I think that works.
Wait and see what the future brings. If a 7th race has intentionally moé females without similarly built males, OK. 'till then, cool your jets a little.
Alka Zolka's intelligence is part of what makes him valuable, if he just focused on physical training he'd be just another meatheaded Marauder! Papashan might be older and past his prime but there's nothing saying he can't go toe to toe with larger foes!
Roegadyn being able to best Lalafell in a contest of sheer physical power is undeniable, but it takes more than brute strength to win a fight.
P.S.
You did not get the Au Ra naming conventions out before the end of the month, so I shall not send you a pizza, XIV devs. However, if you are quick enough I may send you my leftover Costco pizza from tonight. I will probably have it for lunch tomorrow though, so chop chop!