Well, the tabletop included not only macro platforms, but also lance and torpedo platforms. Already during the beta I called for System Defence Fleets, made up of fire ships, armed merchants (transports) and dedicated System Defence Monitors, basically cruisers with the shields and firepower of battlecruisers or even battleships thanks to omitting the warp engine. All of these were present in the tabletop, fire ships and merchants were in the previous video game. So they have everything available.
A battleship is actually pretty bad agains the Ancient One, as the Tyranids are too quick and board Spire to death. Gamey variant: Bring Spire in a light cruiser and warp him out as quickly as possible, and spam Nova Cannons backed up with boarding focused Space Marines, and board the AO to death. Because reducing it to 0 crew kills it. They patched this a bit so it is more difficult now. The other not that gamey variant is to bring Spire and his fleet, Spire in an Apocalypse-class BS, snipe with him while trying to kite away (thanks to the lock on range boost for Apocs this can work in combination with MWJ), and a shitload of cruisers. Strength in numbers. Backed up AGAIN by Space Marines. I did it in my first go this way.
I am generally very reluctant to big changes, but this one seems to be very important, even as a mainly singleplayer guy. Nothing is as frustrating as getting the engine of your glorious battleship knocked out right at the beginning of a battle, be it in MP or SP. Because this makes the big ships basically useless.
Yeah, the Total War series does this. Multiple different unit sizes so you always have up to 20 units per army, but the number of soldiers per unit varies between 40 and 200. I would prefer this for BFGA2 as well as I know my computer could handle bigger battles.