[Fyron]

AstralWanderer:
This is all about relative scale, not about stock hull sizes. Nothing stops a mod from making heavy carriers bigger so they can mount multiple space yards (or adding a "small" SY designed for such unit building roles). We don't necessarily need to force modders to make a (probably non-distinctive) 4th carrier size for that.

The problem with adding "massive" versions of a basic hull type is that with SE4 shipsets, it almost always ended up as just a larger picture of the same thing, maybe with very minor detail modifications. When there are already 3 model types for it, a 4th doesn't necessarily add much variety, but it adds more work for modelers. Worldships are distinctive. Scout/corvette adds a possibility for a small, less combat-oriented military hull design. Juggernaut is certainly less distinctive than the other proposals, but many people seemed to want a large warship hull possibility. Unlike a "massive carrier," it probably has more possibility for uniqueness.

IMO, the name "battlestation" has to go between space station and starbase for purposes of continuity (all previous SE games had them in that order). Again, its just a matter of scale. Make your mod have the battlestations at the stock starbase size, and have starbases be even bigger. Nothing forces a modder to use stock hull sizes for anything; he just needs to maintain the relative size ordering for sensible play.