Security from the pedestrian, but someone in a car could drive to the entrance and detonate the place (in Florida this would be more likely than a pedestrian doing so)....go figure.
Nevertheless, if your entrance has to be set back, it can still be designed pedestrian scale. One design solution to the security issue that you just described would be to set the medical structure back from the street, leaving enough space for infill complementing development that can properly address the street, instead of surface parking. Another solution would be to make the entrance a courtyard area. With a little creativity there are a thousand ways to work things out before putting up blank walls, parking lots and gates.
Although not a hospital, the entrance of Charlotte's Heasrt Tower is an example of setting back something from the street but still incorporating a pedestrian scale design.Unfortunately, in Shand's case (like Jacksonville in general), master planning for community integration is something that hasn't been seriously considered in decades. Even when in the pre 9/11 days. Until we can get the basics right, establishing good connectivity will always be a struggle for the urban core.