What the title says. Tactical battles are so simplistic that designing a specialized unit is, well, not really even possible. If I'm aiming for autocalculation, I design for getting the most efficient "unit weight" for my buck. If I'm designing to be effective in tactical battles, I just pile on as much whoop-ass I can. Get a new tech? Add additional increment of whoop-ass to all newly trained units. What. A. Timesink. Isn't this what we were all dreading from the start might happen? And now that Stardock has changed their tune on the significance of tactical battles, we can continue to expect unit design to be meaningless.
This theme runs throughout Elemental and is the biggest persistent flaw. There are plenty of decisions to make, but very often there are a few obvious "best" decisions" each game or, at the least, the best decision is very obvious. What does this leave us with? Lots of busy work.
Personally, I think unit design beyond minor cosmetics should be left to modders and the game should return to Master of Magic's tried and true method. First, make tactical combat meaningful. If you have to, go ahead and just plagiarize Master of Magic's tactical combat to a tee. In other words, give units conspicuous special abilities that have specialized relevance on the battlefield. Then, add plenty of core units in the game that certain races and civilizations have access to and that become unlocked when you gain a special resource or a certain tech (or can be hired as mercenaries as special moments). Then, use the modding tools to create a vast resevoir of unique units that can be shuffled into each new game to fit certain "niches." Some games you might see Lizard Man Spear Throwers show up at your city. Other games you might see Gnoll Grapplers trudging through the country side.
As of now, however, explicit unit design in Elemental is a drag and a source of imbalance: another feature that produces a burst of intrigue within a casual onlooker, but damages the game.