Maybe a "slouchiness" slider would help, and have it enabled for adults too. I slouch a bit, in spite of my youth. It's just how I am. I try to imply that some (or a lot) of my elders are spry and fit in their old age, and it would be nice if they could keep good posture for their entire lives. But not all of them should be so lucky.
Also, why can't elders have muscle mass? They have the muscle definition sliders enabled, so why not the rest of it? It's a little disheartening to think that my insanely strong adult can work out for all his life, work out even more as an elder, and still lose his sexy muscles just because he got older.
As for the choices in elder clothing, I was planning out some outfits for a future dynasty of mine, and I ended up cracking under pressure when it came to finding things for my elder ladies to wear. At least all adult hair is enabled for elders, or else I'd just give up with playing elders.