The brifters with externally routed shifter cables do NOT have cables going through the hood. This is a 105 5600 shifter:
You do NOT have to take off the derailleur cables to change hoods. You just have to take off the brake cables, and then remove the levers from the handlebars, and then pull the hood off the back of the lever body. The secret to changing hoods, is to squirt some armor all into the inside of the hood. That will make removal and installation way, way easier.