Ike is a fascinating storm to watch on satellite loops. It is really giving a pinwheel effect with two lobes of convection rotating around a small inner core. If you watch closely, you can see those two lobes moving in an almost perfect circle around the center. Recon obs indicate an outer wind maximum at the radius where those lobes are rotating, where the winds have been observed as strong or stronger than in the inner core. That outer radius is almost functioning as a very wide concentric eyewall.

As long as the convection on the outer band of the storm is as strong or stronger than that in the inner core, it will be a struggle for Ike to deepen very rapidly. The system as a whole is becoming stronger, but much of the energy is apparently being used to expand the size of the storm and maintain a large radius of strong winds, rather than being focused near the center. This is probably too simple of an explanation, but Ike's small inner core is basically competing with its outer band right now.

When Ike first hit Cuba, it was in the midst of an eyewall replacement cycle that it never seemed to finish. Ever since then, it seems to have exhibited an outer wind maximum, if not always an outer eyewall. I am not an expert on hurricane dynamics, but I would guess that the disruption from the outer wind max will not go away until an eyewall cycle is completed. Whatever the case, the inner core will have to take over at some point if Ike is going to significantly intensify.