Well, it's a lot easier to have a concealed Melee implant than something that takes ammo. Also, melee weapons in general are a lot less problematical when running into law enforcement.
There are many reasons people wouldn't carry guns unless expecting trouble. Go into a nightclub, for example, or an office building. Very likely to get any guns taken away. Well, any weapons, really, but cyber melee weapons would be hard to detect if they were designed for such.
Also consider that shooting a gang member in the head gets the gang on you - punching them in the head and knocking them out gets that member laughed at. They might come after you, the gang is less likely to. On jobs murder gets much more heat on you than assault.
Lots of reasons for melee.
- Shane