Wow, how many times was the word "trope" used here?
... only 7? Disappointed in you!
Anyway, I think the main thing to keep in mind is that the Au Ra were almost clearly designed with the Raen in mind over the Xaela. +90% positive this is the case; just look at the effort that went into explaining the Raen names vs. the Xaela "use a period Mongolian name and a tribe with a quirky custom." Considering this and the strict gender roles of Japanese society (even in modern times, to a lesser degree) it's not surprising at all the men are big and tough and the women are small, prim, and proper.
Ironic, then, that I've seen more Xaela PCs on my server...
Regardless, while there might be tribes and individuals that fall outside of these boundaries, there is only room for so much variety in the character creator. What we're allowed to create falls within the boundaries of "average" members of the race. There are individuals who fall outside of these boundaries (all of the GC leaders have unique models, for example, and Yugiri has a unique face and horn coloration), but PCs are just that - average.
You keep saying "well, they should make a race of big tough women and smaller men," but if they did that they'd get just as many complaints (if not more). All the boys who play the game as a power fantasy would be up in arms saying stuff like "It doesn't make sense for the women to be big and tough while the men look like scrawny geeks because raisins!" etc etc. No matter what they do everybody isn't going to be happy, so they did the best the could with what they had - unfortunately, this meant making the "tougher" of the two tribes identical to the "gentle" tribe in every way save horn / scale coloration. Since the Raen were clearly the more focused-on of the tribes, and the Raen are part of Hydaelyn!Japanese society...
Could they have differentiated the clans a la Midlanders and Highlanders? Absolutely. Should they have? Probably. There are reasons as to why they didn't, the chiefest likely being they didn't have the time and resources to devote to it with everything else going on. They can't add in special options because then they'd have to add in special options for EVERY race - people would complain they want to play a Lalafell with gigantism, or a Roegadyn with dwarfism, etc. The only options in that case would be to either A) put the time and resources into making those situations work or B) tell people the Au Ra got special treatment and piss them off. Asking for something like that because "well, my Au Ra is from a highly secretive clan with super-tall women" is asking for special snowflake treatment.
Yeah, the Huge Guy, Tiny Girl Bizarre Sexual Dimorphism is overdone and cliché, but that's because it works for good or ill. Ultimately your complaints boil down to "I wanted to play a big, tough dragon lady (not that kind of dragon lady), and female Au Ra don't let me do that," which fair enough, but they aren't exactly what I wanted either. Still, they can't please everyone, and I'm willing to accept what we got. RMT and class balance are another thing entirely - they can be an active detriment to your performance, while the appearance of your character is purely aesthetic (aside from a few starting stat points that end up being negligible by endgame).
Having fun with DRK, but I do want to get on with the story. 4 levels to go. At least I haven't had any bad experiences aside from this one Stone Vigil run with a cocky overgeared BLM who wordlessly decided he was calling the shots because he's overgeared. Feel kind of bad for leaving Alphinaud standing out in the bitter cold though. (Not really, serves him right for leaving his damn coat at the manor! ... but Tataru...)