I wouldn't be surprised to see a section in Run Faster just about runner gear. Chameleon coatings, for instance, aren't restricted just to weapons. Some of the other items, like extended magazines, are so easily done already they might not have thought that it needed explanation. 1 magazine + 1 magazine = extended magazine. Double price, +1 concealment.
As for some of the more exotic modifications, I think the explanation there is that in 4th edition, there were A LOT of goodies to play with, many of which probably didn't get used all that often. So rather than wasting book space with items that people don't use often, they might have opted to spend more time in other areas.
I don't know that I would have spent so much time on demolitions, but that's a decision that's out of my hands. And to be honest, demolitions really can only go in a book about making things go boom.