This isn't a game where all nations are created equal. I think nations that are built on maritime trade needing to focus on having a strong navy would add some realism to the game, and that would be a good thing.
Its the wrong way to go about it. Its like making the Hordes use cavalry by making their infantry useless rather than buffing their cavalry or Russia into the "numbers" nation by making all their troops weaker rather than by giving them extra manpower.
Naval nations have to build a navy, that is already there. An England, Venice, Denmark, Aragon etc that lose naval control in a war are completely screwed, they need their light ships trading, they need to access their colonies and almost every province is coastal so blockades hurt them massively. They already suffer massively because their Army ideas are much weaker than say France, which means they will lose in most fair fights. The fact that they have to maintain a large army just for survival, whilst the damage they can actually do to their opponents with navies is minimal, further harms that balance.
That is also not realistic. Britain fought France on land despite having gone heavily naval ideas, the Ottomans didn't have a bad army because they had a hugely powerful navy, France didn't completely ignore a navy because they only needed armies.
I am not suggesting that all nations are created equal, but making being a naval power a negative thing is not good for the game.
This is how the game used to be. For instance, if Spain and Netherlands were at war, France might give access to Spain but not to Netherlands so only Spanish armies could enter France. The current rules were put in place to help the AI.
If they want to fix military access then they should make it almost impossible to get, wandering half way across the HRE to fight someone should be impossible. Certainly supplying that army there would be.