Not to explain myself and ruin a lot, but they're using technology they have little to no knowledge of. As it was there before they were. A lot has happened in the gray period of time that no one really recalls. As if a lapse in history happened between those x' numbers of years. In primarily of things, it's simple as this. There is no demand for that sort of body modification with the readily available Byts to use it.
Nephilims on the other hand, cannot use cybernetics or bio-tech at all, their body rejects it regardless of the measures. As they do exist, you need to have quite a lot of influence and money to fund it. And forget about getting it installed on the black market. They may might be able to steal it for you, but getting it in you is an adventure of it's own. Now, the only thing that is really readily available is prosthetic replacements. Black market variations would possible have stronger limbs, perhaps something as you'd state, a secret compartment or perhaps electrified attacks, but nothing completely drastic.
Someone could run faster, kick you across the room and electrocute you with a punch, but no shape-shifting or shooting energy bolts out of their hands. As modifications as it is is far and few between unless necessary [as they're expensive regardless, unless on the police force or military, it's in the pension to get replacement parts.
As for other things, having such parts is considered a rather strong social stigma, sure you may have Byts and Nephilims as servants, but now you want to be one too? Type attitude.
But, some things don't work like they do in other games. If I wanted a hard cyber/bio punk type game, I'd run Shadowrun or Cyberpunk 202X.
The genre that NR would fall under would be a mixture of Post-Apoc, Cyber/Bio Punk, Mystery and Horror.