Thoughts about objectives

I agree with you that they objective exist to prevent turtling. Often they are called "top", "center" and "bottom". Not very nautical, however practical!

Yeah, without Objectives, the balance strongly swings towards airpower... hide on the back row and drop in the bombers!

It also depends on your definition of destroyed. If I remember correctly destroyed doesn't automatically mean sunk it means that the ship is no longer capable of fighting.

At that point winning an objective is representative of gaining the upper hand in that area of engagement.

So the objective is more a concept rather than something physical

When my friends & I played, we rarely used objectives. We fought until one side won.
These games may have lasted a little longer, but they were a lot of fun.
I love a good slug-fest!

...where objectives get an additional game mechanic, apart from scoring victory points only once?