It's indeed the way it is so that you can indicate a square that must be water. What you propose sounds like a solver to me, and I much prefer solving it myself.
Note that very often, the solution process for a more difficult puzzle involves going through nontrivial logic to prove that a particular square must be water. It's important to be able to record non-obvious "must be water" squares.
If you do it as a purely visual representation of the game state, it won't be a solver, will it? Just all blocks surrounding ships + blocks in rows/cols with a 0.