A common discussion point carrying a wide range of opinions, it is not our place to say who is wrong & who is right.
If It's Good Enough For.....
All we will say here is that it is a requirement of the Recreational Craft Directive & the American Boat & Yacht Council (ABYC) and the British Marine Electronics Association codes of practice recommend it.
The only practical argument against bonding the earth to the hull is that it can promote galvanic corrosion by effectively turning the boat into a battery. The simple answer to this is to “break” the shore to boat earth by fitting a galvanic isolator or an isolation transformer immediately before the hull bonding point.
Why we would bond to earth is easily justified on the grounds of safety alone. Remember that worse case has to be the starting point for safety. (We won’t go into the realms of single & double insulation here for the sake of simplicity).
Imagine a case where a fault develops on the live wire into the boat and it comes into contact with the hull. (This could easily be a live wire behind a plug socket that has vibrated loose for example).
The hull becomes live, but if it is not bonded to the earth there is no safe path to earth for the stray current.
Someone entering the boat from outside & touching the live hull will come from somewhere at 0V into contact with 230V and will instantly receive an electric shock.
Consult your local marine electrician
to arrange an electrical safety test as part of your maintenance programme.