That's not going to matter much.
Anti-cav is inherently a reactionary unit. There is little point in building them preemptively since they would be useless if the enemy didn't attack or went something else and even if they were built, your opponents are under no obligation to suicide into you due to the superior mobility. So you can't chase them down and you also have no ability to really launch a counteroffensive because they are bad at everything else. Bascially, massing spears and pikes against cavalry overwhelmingly favors the later because they can always take potshots at you and you can't. And this is skewed by the fact that it requires a fairly useless tech.
tl;dr Pikes are easy to counter, when pikes don't really counter knights that well to begin with.
I agree Pikes are useless and the tech should be skipped to allow players to directly upgrade Spearmen into Pike&Shot @ Metal Casting.
Rene. Pike&Shot is where anti-cav will shine as they out-of-the-box beat Ind Cavalry units (65 vs. 62) with their inharent +10 combat str vs. mounted units even without oligarchy's legacy card.
Players can easily build cheap spears and upgrade @ Metal Casting w/ 50% discount. This may not take advantage of the production policy, but you'll get a quick counter unit that has no resource requirements.
In a long drawn out war, the anti-cav will at least require less gpt to maintain.
The movement of mounted units is the largest problem in combating them, but if they intend to take territory/cities they will have to stand and fight some anti-cav units.
I would like to see ZoC effect mounted units if exerted by anti-cav, move up the Redeploy (+1 movement) anti-cav promotion to 1st/2nd tier, or straight up increase anti-cav combat str.
Any of these would make them more useful as a whole.
Perhaps the card will help if you do not have iron? Cannot build swords or knights. So that may make these units worth while for warmongerers?
I also think that the card is a small plus for Gorgo. Hoplites became cheaper to build. The support upgrade for these units is pretty good.
I don't think warmongers will build many anti-cav (except for UUs) as they don't provide enough movement for conquests while they are still relevant. They are defensive units to promoted the turtle/defensive style that R&F promotes and enhances.
Gorgo's UU certainly benefited as it's major limitation was production inefficiency.