Body hair is frighteningly bad and low quality. Back hair is even worse.

It has to do with the art style. The examples of better body hair you showed are considered alpha and does not fit the art style of the game. Sims 3 is also alpha.
I personally never liked maxis match so I can't really comment on it. I'm a 100% alpha girl and will still be using my alpha body hair.
But it's not that they "couldn't do it" it has to do with the style is all I'm saying. When they first mentioned body hair I wondered what it would look like in maxis style....
The werewolf hair also looks very drawn on and cartoony. Not bad thing, it depends on your preferences.

One thing I will say is that they didn't give us "enough" body hair. Especially on the front of the sim. It needs to be filled in more imo.