Gel Coat that has cracks is bad for a number of reasons.  It has very poor cosmetic appearance, show evidence of damage, and does not protect the underlying structure as intended.

The good news is that these cracks can be repaired. The bad news is that the repair process is a bit involved, and requires the application of a new surface coating: new gelcoat, paint, or something similar like Awlgrip.

 

Youtube Yachtorial demonstrates some basic strategy and materials to do such a repair.