Land is like 75%+ of the units made in the game, no faction can “excel at land” without being meta defining. Likewise your analysis of one faction being good at air, one good at navy, and one good at land, even if we were to assume your takes are right, would make this game completely boring. It would be defined by the faction and map you rolled at 0:00 and at that point you might as well as quit the game. Also, what the hell does that make Seraphim good at? Space?
Every faction has comparative advantages at different points, UEF has a strong t2 air stage except against Aeon who no faction can compete against assuming equal prioritization on t2 air. So now your gameplay is ‘t focused on leveraging a total air win but rather low cost yet mass efficient engagements that force an overinvestment into air you never intended to fight. Instead you put your win condition elsewhere.