The problem most people here have with your logic is that the difference between class 4 and class 5 is not in size, but rather building style and effect on performance. It is incredibly easy to have a class 6 ship that is cheaper than a well built class 3. Class also does not indicate combat performance.
For example, LoT has two primary classes of ships that we use, cerberus and roar. Cerberus designed by myself and Roar by @Lindenn. Each has more than 8 major versions and revisions, updating to reflect different ideas and combat mechanic changes. Currently the most recent version of each is the same basic size ship, and max turrets. Each has comparable survivability, the biggest difference is in function. They each are around 100k iron to build. But here is the kicker. Cerberus is class 3, and roar is just barely under class 4. I wont go into why, but it has nothing to do with either being a lumbering giant, or us wanting to dominate with preparation. It is building style differences. I have exactly 26 6 way cylinder connectors in Cerberus. It is actually larger in sheer block size and devices. Roar uses as many as is allowed for combat buffering, and as such has less issues with lag shots in our tests.
This is anectdotal evidence obviously, but dont go jumping to conclusions that the reason people want classes is so they can have an “unfair advantage”. It is just a little more leeway in building style when you get down to it. Cerberus regularly beats cv’s of class 5 or 6 in our tests.
When it comes to bases though, this all is irrelevant. You can have a class 1 or 2 base with max turrets and a buried core, that will last just as long as a headquarters of class 8. And you wont see these bases flying around in pvp, causing frame rate drops. Obviously you want limits of some sort to keep neighbor living a little more bearable. But dont try and tell me that it has anything to do with an unfair advantage there.