With the exception of Georgia traveling the AICW is actually SHORTER in distance that going 'outside'. By going 'outside' you will invariably be forced to go additional long distances through the inlets, etc. and that stacks up to a LONGER ride.
The benefit of going outside is that you can sail continuously for days if necessary. So if you prefer to anchor each evening, then (with the exception of crossing GA) its 'shorter' and less distance overall to follow the ICW in most cases - due to the 'length of MOST inlets'. The ICW in NC (south of Beaufort), SC , Northern FL, is essentially a 'straight shot'. Charleston, Tybee, Waccamaw, Port Royal, Beaufort SC, etc. inlets are LONG distance inlets,