The firing mechanic just doesn't feel smooth and reliable. It's almost exactly like the old Ogris firing mechanic with the minor change that partially charged shots fire off a much weaker shot. This firing mechanic was scrapped for good reason, not sure why it was brought back on another weapon. The quickshot is an improvement compared to the old Ogris jamming but it's damage and fire rate are underwhelming and probably not meant to be a real alternative to charged shots. And to add insult to injury a partially charged shot is a complete waste since quickshots don't scale at all with any charge.
Now you might point to the Opticor and say it works for that weapon but that's a hitscan punch through beam that deals much more damage (or fires much faster in the case of the vandal) not an explosive projectile with travel time. Also quickshots with the Opticor do scale with how much charge you have.