Thing is though, like you said a shot in the arms or legs wasn't an instant kill, so it just shifted the balance in favour of the rapid fire guns IMO because you might as well not use the bolts because with the rapid fire weapons were nearly as accurate as bolts, you can spam so you don't have to worry about the aim so much and you reset the health regen with each shot. This is in multiplayer anyway.
It also meant that you could run around oblivious, get shot by a bolt, hide for a sec to get your health replenshished, then go and investigate and use your uber spray and pray skills to kill the guy.
Also people hardly ever took the bolt rather than the semi-auto because you could shoot like 5 shots as accurately for slightly less damage in the space of time you could shoot 2 from the bolt.